Monad

Monad (μονάς monas) is a Greek word for "unit". With the Pythagoreans it was a term for Divinity, the source or the One.

In Theosophy monad refers to the two highest principles, atman and buddhi. The monad, compelled by the circle of necessity, engages in a process of evolution from which emerges as a triad after assimilating the essence of manas during the stage of human evolution:

Monad (Gr.). The Unity, the one; but in Occultism it often means the unified triad, Atma-Buddhi-Manas, or the duad, Atma-Buddhi, that immortal part of man which reincarnates in the lower kingdoms, and gradually progresses through them to Man and then to the final goal— Nirvâna.

The dual Monad

atman and buddhi, being universal, are not endowed with individual consciousness. Therefore the dual Monad is not conscious:

The sixth and seventh principles apart from the rest constitute the eternal, imperishable, but also unconscious “Monad.” (K.H, cML 68)

The triple Monad

When the dual Monad absorbs the highest attributes of the fifth principle or manas, it becomes conscious:

To awaken in it [the Monad] to life the latent consciousness, especially that of personal individuality, requires the monad plus the highest attributes of the fifth [principle]. (K.H, cML 68)