Sri Aurobindo translates Shwetashwatara Upanishad, Chapter Six, Verses 3-4: “The Lord doeth works and resteth again from His works, one or two or three or eight. He yoketh Himself with the Principle of things in their essence and with Time He yoketh Himself and with Self in its subtle workings. So He beginneth works that are subject to the Modes of Nature, and setteth all existences to their workings: and when these things are not, thereby cometh annihilation of work that hath been done; and with the perishing of work, He departeth out of them; for in His final truth He is other than they.”
The Upanishads were not meant to be systematic written texts but rather notes and guidelines to a teaching that was oral and transmitted directly from the Guru to the disciples. Certain verses, therefore, are somewhat difficult to understand when they enumerate items without specific reference, as we find here. Some commentators speculate on the meanings of the numbers cited, based on traditional context. An example of this type of extrapolation is found in the number 8 cited here. In the Bhagavad Gita, the creation is said to consist of the five great elements, ether, air, fire, water and earth, along with Manas (mind), Buddhi (higher reason) and Ahankara (ego-sense). Simillarly the three likely relates to the 3 modes of Nature, Sattwa, Rajas and Tamas, since they are specifically referenced here. (Other commentators hold the 3 to reference the 3 bodies, physical, subtle and causal.)
Some commentators reference the number 1 as ignorance, and the number 2 as Dharma and Adharma, essentially the power of past acts to form future consequences through the action of Karma. . It is however equally possible that given the description here of the subtle processes of the Creation, that the 1 is the Eternal and the 2 is the development of the bifurcation into Purusha and Prakriti, the Witness consciousness and the active power of consciousness in Nature.
The Upanishad indicates that the Lord sets the action of the worlds in motion. The action of the three Gunas, modes of Nature, in their constant changes, leads to the entire “work” of the worlds, and when they reach equilibrium, and no changes take place, then the “work” of the world subsides. The Lord, while containing, creating, and enlivening the universe, yet remains transcendent and is not dependent on the universe for His existence.
The Indian tradition holds that the worlds undergo a series of births and annihilations and that this process is based on the Will of the Lord, acting through the Gunas. The Lord sets the subtle action in motion and the evolutionary development process then takes place with the support, and attention of the divine Presence.
Sri Aurobindo, The Upanishads, Shwetashwatara Upanishad, pp.369-384