Within the Theosophical worldview, the entire cosmos is understood to unfold according to a fundamental law of cyclic periodicity. Manifestation proceeds in alternating phases of activity and repose, termed Manvantara and Pralaya, which apply at many levels: to universes, solar systems, planets, and even to the evolution of humanity itself. These immense cycles are sometimes spoken of in terms of Kalpas, vast “cosmic days” during which worlds emerge, develop, and eventually withdraw again into latency. Rather than a linear progression, existence is portrayed as a rhythmic advance, with repeated descents into matter followed by corresponding re-ascent toward spirit.

On the planetary level, this cyclic law is expressed through the doctrine of Root Races, which functions as a teaching about world ages. Humanity unfolds through seven great Root Races during a planetary Manvantara, each Root Race lasting for immense spans of time and being further articulated into sub-races, and even more finely into branch and family races. These Root Races are not merely physical groupings but stages in the evolution of consciousness and form. The first and second are described as ethereal or semi-physical, while the third, often associated with Lemuria, marks a decisive descent into physicality and the emergence of individual mind. The fourth, linked with Atlantis, represents a peak of material development and psychic power, followed by decline, and the present humanity is regarded as the fifth, or Aryan, Root Race, oriented toward mental and self-conscious development.

Theosophy also adopts and reinterprets the traditional Hindu schema of the four yugas—Satya (or Krita), Treta, Dvāpara, and Kali—as another expression of these world ages. Each yuga signifies a phase in the balance between spiritual clarity and material obscuration: Satya Yuga as an age of truth and spiritual luminosity, Treta and Dvāpara as stages of gradual decline, and Kali Yuga as a period of pronounced materialism and spiritual dimming. These yugas are seen as nested within the larger patterns of Root Races and planetary cycles, so that even within a single Root Race there are recurring rises and falls in spiritual opportunity.

All of these interlocking cycles—cosmic Manvantaras and Pralayas, planetary chains and their Rounds, Root Races with their sub-races, and the succession of yugas—are interpreted as serving a single overarching purpose: the evolution of consciousness. Spiritual monads pass through kingdoms of nature and through the successive stages of human development, gaining experience as they move along the great arc of descent into matter and the corresponding arc of return toward spirit. Nothing essential is lost in these vast alternations of manifestation and withdrawal; each new cycle resumes the work of the previous one at a higher turn of the spiral, so that the universe itself becomes a grand school for the unfolding of latent spiritual potential.