Lust is a psychological force producing intense desire for an object, or circumstance while already having a significant amount of the desired object. Lust can take any form such as the lust for sexuality (see libido), money, or power. It can take such mundane forms as the lust for food (see gluttony) as distinct from the need for food or lust for redolence, when one is lusting for a particular smell that brings back memories. It is similar to but distinguished from passion, in that passion propels individuals to achieve benevolent goals whilst lust does not.
Religions tend to draw a distinction between passion and lust by further categorizing lust as an immoral desire and passion as morally accepted.
Lust is defined as immoral because its object or action of affection is improperly ordered according to natural law and/or the appetite for the particular object (eg sexual desire) is governing the person's intellect and will rather than the intellect and will governing the appetite for that object.
Whereas passion, regardless of its strength is maintained to be something God-given and moral, because the purpose, actions and intentions behind it are benevolent and ordered toward creation, while also being governed by the person's intellect and will. A primary school of thought on this is Thomism, which speaks on the intellect, will and appetite, and draws from principles defined by Aristotle. However, the exact definitions assigned to what is morally definite and ordered toward creation depend on the religion. For example, differences between religions based in pantheism and theism will differ what is moral according to the nature of the "God" acknowledged or worshipped.
In Judaism, all evil inclinations and lusts of the flesh are characterized by Yetzer hara (Hebrew, , the evil inclination). Yetzer hara is not a demonic force; rather, it is man's misuse of the things which the physical body needs to survive, and is often contrasted with yetzer hatov (Hebrew, ?, the positive desire).
Yetzer HaRa is often identified with Satan and the angel of death, and there is sometimes a tendency to give a personality and separate activity to the yetzer. For the yetzer, like Satan, misleads man in this world, and testifies against him in the world to come. The yetzer is, however, clearly distinguished from Satan, and on other occasions is made exactly parallel to sin. The Torah is considered the great antidote against this force. Though, like all things which God has made, the yetzer hara (evil inclination) can be manipulated into doing good: for without it, man would never marry, beget a child, build a house, or occupy himself in a trade.
Ye have heard that it was said by them of old time, Thou shalt not commit adultery: But I say unto you, That whosoever looketh on a woman to lust () after her hath committed adultery with her already in his heart.
In English-speaking countries, the term "lust" is often associated with sexual desire, probably because of this verse. However, just as the English word was originally a general term for 'desire', the Greek word was also a general term for desire. The LSJ lexicon suggests "set one's heart upon a thing, long for, covet, desire" as glosses for , which is used in verses that clearly have nothing to do with sexual desire. In the Septuagint, is the word used in the commandment to not covet:
You shall not covet your neighbour's wife; you shall not covet your neighbour's house or his field or his male slave or his female slave or his ox or his draft animal or any animal of his or whatever belongs to your neighbour.-- Exodus 20:17, New English Translation of the Septuagint
While coveting your neighbour's wife may involve sexual desire, it's unlikely that coveting a neighbour's house or field is sexual in nature. And in most New Testament uses, the same Greek word, , does not have a clear sexual connotation. For example, from the American Standard Version the same word is used outside of any sexual connotation:
According to the Catholic Encyclopedia, a Christian's heart is lustful when "venereal satisfaction is sought for either outside wedlock or, at any rate, in a manner which is contrary to the laws that govern marital intercourse". Pope John Paul II said that lust devalues the eternal attraction of male and female, reducing personal riches of the opposite sex to an object for gratification of sexuality.
Lust is considered by Catholicism to be a disordered desire for sexual pleasure, where sexual pleasure is "sought for itself, isolated from its procreative and unitive purposes". In Catholicism, sexual desire in itself is good, and is considered part of God's plan for humanity. However, when sexual desire is separated from God's love, it becomes disordered and self-seeking. This is seen as lust.
St. Thomas Aquinas differentiates between sexual intercourse within marriage, which is seen as meritorious through giving justice to one's spouse, and sins of lust which can themselves be differentiated in magnitude of immorality according to intention and action. For example, Aquinas says in the Summa Theologica II-II, q. 154, a. 12 "I answer that, In every genus, worst of all is the corruption of the principle on which the rest depend. Now the principles of reason are those things that are according to nature, because reason presupposes things as determined by nature, before disposing of other things according as it is fitting." He uses St. Augustine as his source writing "Augustine says that 'of all these,' namely the sins belonging to lust, 'that which is against nature is the worst.'" Which St. Thomas clarifies means that they are greater than sins against justice pertaining to the genus of lust, such as rape or incest, in his statement "Reply to Objection 3: The nature of the species is more intimately united to each individual, than any other individual is. Wherefore sins against the specific nature are more grievous." Thus St. Thomas gives the order of magnitude of lustful acts as: "The most grievous is the sin of bestiality, because use of the due species is not observed...(Then) the sin of sodomy, because use of the right sex is not observed...(Then) the sin of not observing the right manner of copulation (or the unatural act or masturbation)... (Then) incest... is contrary to the natural respect which we owe persons related to us... Then, it is a greater injustice to have intercourse with a woman who is subject to another's authority as regards the act of generation, than as regards merely her guardianship. Wherefore adultery is more grievous than seduction. And both of these are aggravated by the use of violence." 
The Latin for extravagance (Latin: luxuria) was used by St. Jerome to translate a variety of biblical sins, including drunkenness and sexual excess. Gregory the Great placed luxuria as one of the seven capital sins (it is often considered the least serious of the seven deadly sins), narrowing its scope to disordered desire, and it was in this sense that the Middle Ages generally took luxuria, (although the Old French cognate was adopted into English as luxury without its sexual meaning by the 14th century).
In Romanesque art, the personified Luxuria is generally feminine, often represented by a siren or a naked woman with breasts being bitten by snakes. Prudentius in his Psychomachia or 'Battle of the Soul' had described
Luxury, lavish of her ruined fame, Loose-haired, wild-eyed, her voice a dying fall, Lost in delight....
For Dante, Luxuria was both the first of the circles of incontinence (or self-indulgence) on the descent into hell, and the last of the cornices of Mount Purgatory, representing the excessive (disordered) love of individuals; while for Edmund Spenser, luxuria was synonymous with the power of desire.
For Gregory and subsequent Thomists, the 'daughters' (by-products) of Luxuria included mental blindness, self-love, haste, and excessive attachment to the present. Marianne Dashwood has been seen as embodying such characteristics for a later age - as a daughter of Luxuria.
The Catholic Church defines lust as the idolatry of sexual pleasure, in all of its forms: contraception, masturbation, adultery, premarital relations, relations between persons of the same sex, etc, which destroys the human capacity of loving, that is, of the person to give herself to God and to others.
The evangelical Melvin Tinker states that: "The principle is clear isn't it, 'You shall not commit adultery'? How does the Pharisee handle it according to the minimum requirement method? He says, 'Sex outside marriage is OK for us because neither of us are really married. I am not sleeping with another man's wife, so it isn't adultery, she's my girlfriend'. Or it is also not adultery because 'I have not had sex with that woman.' to quote President Clinton's plea in the Monica Lewinski [sic] saga. So he can abuse his position as President by messing around with a girl who is hardly younger than his daughter, he can engage in all kinds of sexual activities with her, but because he technically doesn't have intercourse he can hold up his hands and say, 'I have not had sex with that woman.' That is a Pharisee speaking.
"But the maximum application method says, adultery doesn't just happen when you have sexual intercourse, it happens in your heart. However, the mistranslation is unfortunate at this point. In the Greek it says, 'If anyone looks upon a woman in order to lust, has already committed adultery with her in his heart.' That is an important distinction. I need to point that out because sexual arousal, sexual interest, sexual attraction are essential for the continuation of the human species... It is about looking in order to lust. The striptease show, the dirty movie or video, the internet pornography. That is becoming a real problem... And if this is a difficulty for you, then do talk to someone about it in confidence. You see, it is the intending to look in order to have that arousal that Jesus has in his sights."
In Islam, lust is considered one of the primitive states of the self, called the nafs. Muslims are encouraged to overcome their baser instincts and intentional lascivious glances are forbidden. Lascivious thoughts are disliked, for they are the first step towards adultery, rape and other antisocial behaviors. Prophet Muhammad also stressed the magnitude of the "second glance", as while the first glance towards an attractive member of the opposite sex could be just accidental or observatory, the second glance could be that gate into lustful thinking.
Arjuna said: O descendant of Vrsni, by what is one impelled to sinful acts, even unwillingly, as if engaged by force? Then Krishna said: It is lust only, Arjuna, which is born of contact with the material mode of passion and later transformed into wrath, and which is the all-devouring sinful enemy of this world. As fire is covered by smoke, as a mirror is covered by dust, or as the embryo is covered by the womb, the living entity is similarly covered by different degrees of this lust. Thus the wise living entity's pure consciousness becomes covered by his eternal enemy in the form of lust, which is never satisfied and which burns like fire. The senses, the mind and the intelligence are the sitting places of this lust. Through them lust covers the real knowledge of the living entity and bewilders him. Therefore, O Arjuna, best of the Bharatas, in the very beginning curb this great symbol of sin--(lust) by regulating the senses, and slay this destroyer of knowledge and self-realization. The working senses are superior to dull matter; mind is higher than the senses; intelligence is still higher than the mind; and he [the soul] is even higher than the intelligence. Thus knowing oneself to be transcendental to the material senses, mind and intelligence, O mighty-armed Arjuna, one should steady the mind by deliberate spiritual intelligence and thus--by spiritual strength--conquer this insatiable enemy known as lust. (Bhagavad-Gita, 3.36-43)
In this ancient manuscript the idea behind the word 'Lust' is best comprehended as the psychological force called 'Wanting'.
Lust holds a critical position in the philosophical underpinnings of Buddhist reality. It is named in the second of the Four Noble Truths, which are that
Lust is the attachment to, identification with, and passionate desire for certain things in existence, all of which relate to the form, sensation, perception, mentality, and consciousness that certain combinations of these things engender within us. Lust is thus the ultimate cause of general imperfection and the most immediate root cause of a certain suffering.
The passionate desire for either non-existence or for freedom from lust is a common misunderstanding. For example, the headlong pursuit of lust (or other "deadly sin") in order to fulfill a desire for death is followed by a reincarnation accompanied by a self-fulfilling karma, resulting in an endless wheel of life, until the right way to live, the right worldview, is somehow discovered and practiced. Beholding an endless knot puts one, symbolically, in the position of the one with the right worldview, representing that person who attains freedom from lust.
In existence are four kinds of things that engender the clinging: rituals, worldviews, pleasures, and the self. The way to eliminate lust is to learn of its unintended effects and to pursue righteousness as concerns a worldview, intention, speech, behavior, livelihood, effort, mindfulness, and concentration, in the place where lust formerly sat.
In Sikhism, lust is counted among the five cardinal sins or sinful propensities, the others being wrath, ego, greed and attachment. Uncontrollable expression of sexual lust, as in rape or sexual addiction, is an evil.
For this reason followers do not eat onions, garlic, eggs, or non-vegetarian food, as the "sulphur" in them can excite sexual lust in the body, otherwise bound to celibacy.
The Brahma Kumaris teaches that sexuality is foraging about in a dark sewer. Students at Spiritual University must conquer lust, to prevent sin, and in order to be closer to god.
The spiritual teacher Meher Baba described the differences between lust and love:
In lust there is reliance upon the object of sense and consequent spiritual subordination of the soul to it, but love puts the soul into direct and co-ordinate relation with the reality which is behind the form. Therefore, lust is experienced as being heavy and love is experienced as being light. In lust there is a narrowing down of life and in love there is an expansion in being...If you love the whole world you vicariously live in the whole world, but in lust there is an ebbing down of life and a general sense of hopeless dependence upon a form which is regarded as another. Thus, in lust there is the accentuation of separateness and suffering, but in love there is the feeling of unity and joy....
Few ancient, pagan religions actually considered lust to be a vice. The most famous example of a widespread religious movement practicing lechery as a ritual is the Bacchanalia of the Ancient Roman Bacchantes. However, this activity was soon outlawed by the Roman Senate in 186 BC in the decree Senatus consultum de Bacchanalibus. The practice of sacred prostitution, however, continued to be an activity practiced often by the Dionysians.
Medieval prostitutes lived in officially sanctioned "red light districts". In Ruth Mazo Karras' book Common Women, the author discusses the meaning of prostitution and how people thought the proper use of prostitutes by unmarried men helped contain male lust. Prostitution was thought of as having a beneficial effect by reducing the sexual frustration in the community.
From Ovid to the works of les poètes maudits, characters have always been faced with scenes of lechery, and long since has lust been a common motif in world literature. Many writers, such as Georges Bataille, Casanova and Prosper Mérimée, have written works wherein scenes take place at bordellos and other unseemly locales.
The more a man cultivates the arts, the less randy he becomes... Only the brute is good at coupling, and copulation is the lyricism of the masses. To copulate is to enter into another--and the artist never emerges from himself.
The most notable work to touch upon the sin of lust, and all of the Seven Deadly Sins, is Dante's la Divina Commedia. Dante's criterion for lust was an "excessive love of others", insofar as an excessive love for man would render one's love of God secondary.
In the first canticle of Dante's Divine Comedy--the Inferno--the lustful are punished by being continuously swept around in a whirlwind, which symbolizes their passions. The damned who are guilty of lust, like the two famous lovers, Paolo and Francesca, receive what they desired in their mortal lives, their passions never give them rest for all eternity. In Purgatorio, of the selfsame work, the penitents choose to walk through flames in order to purge themselves of their lustful inclinations.
The link between love and lust has always been a problematic question in philosophy.
Schopenhauer notes the misery which results from sexual relationships. According to him, this directly explains the sentiments of shame and sadness which tend to follow the act of sexual intercourse; for, he states, the only power that reigns is the inextinguishable desire to face, at any price, the blind love present in human existence without any consideration of the outcome. He estimates that a genius of his species is an industrial being who wants only to produce, and wants only to think. The theme of lust for Schopenhauer is thus to consider the horrors which will almost certainly follow the culmination of lust.
St Thomas Aquinas defines the sin of lust in questions 153 and 154 of his Summa Theologica. Aquinas says the sin of lust is of "voluptuous emotions", and makes the point that sexual pleasures, "unloosen the human spirit", and set aside right reason (pg. 191). Aquinas restricts lust's subject matter to physical desires specifically arising from sexual acts, but he does not assume all sex-acts are sinful. Sex is not a sin in marriage, because sex is the only way for humans to reproduce. If sex is used naturally and the end purpose is reproduction there is no sin. Aquinas says, "if the end be good and if what is done is well-adapted to that, then no sin is present" (pg. 193). However, sex simply for the sake of pleasure is lustful, and therefore a sin. A man who uses his body for lechery wrongs the Lord.
Sex may have the attributes of being sinless; however, when a person seeks sex for pleasure, he or she is sinning with lust. Lust is best defined by its specific attribute of rape, adultery, wet dreams, seduction, unnatural vice, and simple fornication.
Wet dreams: St Thomas Aquinas defined and discussed the topic of nocturnal emission, which occurs when one dreams of physical pleasure. Aquinas argues those who say that wet dreams are a sin and comparable to the actual experience of sex are wrong. Aquinas believes that such an action is sinless, for a dream is not under a person's control or free judgment. When one has a "nocturnal orgasm", it is not a sin, but it can lead to sins (pg. 227). Aquinas says that wet dreams come from a physical cause of inappropriate pictures within your imagination, a psychological cause when thinking of sex while you fall asleep and a demonical cause whereby demons act upon the sleeper's body, "stirring the sleeper's imagination to bring about a orgasm" (pg. 225). In the end, though, dreaming of lustful acts is not sinful. The "mind's awareness is less hindered", as the sleeper lacks right reason; therefore, a person cannot be accountable for what they dream while sleeping (pg. 227).
Adultery: One of the main forms of lust seen frequently during the Middle Ages was the sin of adultery. The sin of adultery occurs when a person is unfaithful to his or her spouse, hence "invading of a bed not one's own" (pg. 235). Adultery is a special kind of ugliness and many difficulties arise from it. When a man enters the bed of a married woman it not only is a sin, but it "wrongs the offspring", because the woman now calls into question the legitimacy of children (pg. 235). If a wife has committed adultery before, then, her husband will question if all his wife's children are his offspring.
Simple fornication: Simple fornication is having sex with one's wife for enjoyment rather than for bearing children. Fornication is also sex between two unmarried people, which is also a mortal sin. Aquinas says that "fornication is a deadly crime" (pg. 213). Fornication is a mortal sin, but as Aquinas notes, "Pope Gregory treated sins of the flesh as less grievous than those of the spirit" (pg. 217). Fornication was a grave sin such as that against property. Fornication, however, is not as grave as a sin directly against God and human life; therefore, murder is much worse than fornication. Property in this case means that a daughter is the property of her father, and if one does wrong to her, one then does wrong to him; therefore seducing a virgin or seeking pleasure from an unmarried woman is an invasion of a father's property.
Rape: Rape is a kind of lust that often coincides with seduction and is defined as a type of lechery. Rape comes with force and violence: Rape occurs when a person craves the pleasures of sex so intensely that he uses force to obtain it. Rape is committed when violence is used to seduce, or deflower a virgin. Rape harms both the unmarried girl and her father, because the girl is property of her father. Rape and seduction can be discussed together, because both sins involve the deflowering of a virgin; however, rape can happen without seduction, as when a man attacks a widow or a sexually experienced woman and violates her. Therefore, wherever violence accompanies sex, you have the quality of rape and the sin of lust.
Seduction: Seduction is a type of lust, because seduction is a sex act, which ravishes a virgin. Lust is a sin of sexual activity, and "...a special quality of wrong that appears if a maid still under her father's care is debauched" (pg. 229). Seduction involves a discussion of property, as an unmarried girl is property of her father. A virgin, even though free from the bond of marriage, is not free from the bond of her family. When a virgin is violated without a promise of engagement, she is prevented from having honorable marriage, which is shameful to herself and her family. A man who performs sexual acts with a virgin must "endow her and have her to wife", and if the father, who is responsible for her, says no, then a man must pay a dowry to compensate for her loss of virginity and future chance of marriage. (pg. 229)
Unnatural vice: Unnatural vice is the worst kind of lust because it is unnatural in act and purpose. Many varieties of unnatural vice exist; Aquinas provides several examples, including bestiality or intercourse with a "thing of another species" (for example, an animal), incest, sodomy and "not observing the right manner of copulation".