Masters of Wisdom

The Masters of Wisdom, or simply "The Masters" are initiates in the occult science and esoteric philosophy who take disciples or chelas. H. P. Blavatsky, in the glossary of her book The Key to Theosophy defined the Theosophical concept of "Master" as follows:

Master. A translation from the Sanskrit Guru, "Spiritual teacher," and adopted by the Theosophists to designate the Adepts, from whom they hold their teachings.

The Masters of Wisdom are sometimes referred indistinctly as "Brothers", "Adepts", or "Mahatmas." However, it seems the word "Master" refers more specifically to a high class of Adepts who work in line with the evolutionary movement. This idea is reported by Charles Johnston in his interview to Mme. Blavatsky:

Then she told me something about other Masters and adepts she had known--for she made a difference, as though the adepts were the captains of the occult world, and the Masters were the generals.