The common definition of celibacy:
Celibacy is often confused with chastity. They are related, but very distinct. Learn more: What is Chastity?
In the esoteric tradition, it is known that there are two forms of celibacy.
Solar celibacy is a positive type of sexual life, in which an individual refrains from sexual union and masturbation, replacing them with spiritual exercises that transmute the sexual matter. Unfortunately, many modern groups have abandoned these types of exercises, so that their celibates no longer have the tools to manage their sexual energy effectively, thus they are practicing the lunar type of celibacy. What modern people usually call "celibacy" is actually a state of sexual repression, called in esotericism "lunar brahmacharya," whose results speak for themselves with the infamous perversities of priests, monks, and nuns who abuse children and each other, by means of homosexuality and masturbation. In addition, those who repress their sexual forces suffer mental imbalances, leaning towards anger, violence, fanaticism, and cruelty. The Inquisition, "religious" tortures, and various types of religious wars stand as clear examples of results of lunar celibacy.
"The lunar type [of celibacy] is that absurd sexual abstinence that serves only to produce filthy, nocturnal sexual pollutions with all of its fatal consequences." - Samael Aun Weor
In ancient times, sexual abstention (celibacy) was only observed in certain cases:
Celibacy or sexual abstention - properly utilized and guided - is an important aspect of spiritual life. A single person can develop a great deal of self-knowledge, as Paramahansa Yogananda did. However, it should be noted that he refused the higher teachings of sexual cooperation, and thus could not advance further (the masters of his Kriya Yoga lineage practiced with their wives, but with Yogananda, that tradition ended).
Marriage - the sacrament of sexual union - has always been a sacred institution whose spiritual importance was emphasized in all religions. In all ancient traditions, the highest spiritual leaders were always married, even if secretly. Many famous "celibates" practiced sexual cooperation in secret. A key example is Sri Ramakrishna who practiced sacred sexuality devotedly with his partner.
"According to Indian tradition, Ramakrishna had Sarada Devi sit on the throne of the Divine Mother within the temple. At the same time, he began to sing the hymn to Devi Kundalini with the ancestral ritual ceremony, which culminated in the famous Shorashi Puja, the adoration of woman. He and she achieved Samadhi during the Maithuna..." - Samael Aun Weor, The Mystery of the Golden Flower (1972)
One cannot reach the heights of the path alone. In the beginning of spiritual life, many need a time of preparation for sexual cooperation. This is why brahmacharya or celibacy has long been instituted. Yet, through celibacy, one cannot master the sexual powers, which create life in the superior worlds.
"There were also some hallucinated mystics who pleaded in favor of an absurd type of chastity [without transmutation], which some religious sects preach, but do not practice. They ignore that Nature is in rebellion against that harmful abstinence, which causes nocturnal pollutions and the decalcification of the organism through the urethra. Sickness is the consequence.
"Men were made for women and women for men, because Nature is wise in its designs. What man and woman have to learn is to enjoy themselves without hurting each other, and the answer for this is Sexual Magic. During the act of love, the Gnostic couple transmutes their semen into atomic energy by restraining the sexual act. This energy then rises upwards towards their head, through certain spermatic canals." - Samael Aun Weor, The Revolution of Beelzebub (1950)
"We met a terribly mystical, wretched old woman who looked at sex with repugnance, as something vulgar, dirty, and gross. She considered herself to be [celibate] totally chaste and pure. When we studied her Satan (her Guardian of the Threshold) in order to know her purifications, we were surprised and had to defend ourselves, since her Satan attacked us in a horrible manner. The sexual appetite of that wretched soul was terrible. What happened is that the body of that sick old woman was no longer functional for her passionate satisfactions, that was all.
"Many state, “Sex is vulgar. I am [celibate] chaste and pure. I am very spiritual. I am no longer enticed by the lewdness of sex,” etc. Yet, when we examine the Satan of those “super-transcended mystics,” we verify that those souls are filled with a terribly suppressed sexual appetite. Within the fornicators, Satan is very robust and strong.
"Only those who manage to ride the donkey, only those who tame the beast, are capable of transforming their Satan into a beautiful child filled with beauty. But we have to ride the donkey. We must practice sexual magic, to really face the beast in order to tame it and overcome it. This is the only way to attain chastity." -Samael Aun Weor, The Major Mysteries