The teachings we study here have been safeguarded by the greatest human beings who ever lived.
Gnostics: those who embody the highest ethical and spiritual values, such as temperance, diligence, humility, chastity, generosity, etc. To understand what a Gnostic is, you must first understand what Gnosis is.
Throughout our entire history, there has been a protected and difficult to acquire knowledge. Those who received it had to prove themselves worthy through their ethics and their capacity for sacrificing for others. Thus, those who received this knowledge, and in turn carried forward to the next generations, were the greatest artists, philosophers, musicians, scientists, religious leaders, and more, both men and women, and from every culture and civilization in the world. These are but a few of those who knew and practiced Gnosis, even when it was known by other names, such as Dharma, Torah, Daath, Jnana, Tantra, etc. As you would expect, most were sworn to secrecy.
"When confronted with a problem involving the use of the reasoning faculties, individuals of strong intellect keep their poise, and seek to reach a solution by obtaining facts bearing upon the question. Those of immature mentality, on the other hand, when similarly confronted, are overwhelmed. While the former may be qualified to solve the riddle of their own destiny, the latter must be led like a flock of sheep and taught in simple language. They depend almost entirely upon the ministrations of the shepherd. The Apostle Paul said that these little ones must be fed with milk, but that meat is the food of strong men. Thoughtlessness is almost synonymous with childishness, while thoughtfulness is symbolic of maturity.
"There are, however, but few mature minds in the world; and thus it was that the philosophic-religious doctrines of the pagans were divided to meet the needs of these two fundamental groups of human intellect--one philosophic, the other incapable of appreciating the deeper mysteries of life. To the discerning few were revealed the esoteric, or spiritual, teachings [Gnosis], while the unqualified many received only the literal, or exoteric, interpretations. In order to make simple the great truths of Nature and the abstract principles of natural law, the vital forces of the universe were personified, becoming the gods and goddesses of the ancient mythologies. While the ignorant multitudes brought their offerings to the altars of Priapus and Pan (deities representing the procreative energies), the wise recognized in these marble statues only symbolic concretions of great abstract truths.
"In all cities of the ancient world were temples for public worship and offering. In every community also were philosophers and mystics, deeply versed in Nature's lore. These individuals were usually banded together, forming seclusive philosophic and religious schools. The more important of these groups were known as the Mysteries. Many of the great minds of antiquity were initiated into these secret fraternities by strange and mysterious rites, some of which were extremely cruel. Alexander Wilder defines the Mysteries as "Sacred dramas performed at stated periods. The most celebrated were those of Isis, Sabazius, Cybele, and Eleusis." After being admitted, the initiates were instructed in the secret wisdom [Gnosis] which had been preserved for ages." - Manly P. Hall, The Secret Teachings of All Ages (1923)