The Upanishads make a statement to the sense of “This is the complete; That is the complete. Take the complete from the complete, and the complete remains.” Sri Aurobindo follows up on this sense in his discussion of the integrality of Brahman. “Brahman, as he exceeds the passivity and the activity, so too exceeds the unity and multiplicity. He is one in himself, but not with a self-limiting unity exclusive of the power of multiplicity, such as is the separated unity of the body and the mind; he is not the mathematical integer, one, which is incapable of containing the hundred and is therefore less than the hundred. One in himself, he is one in the many and the many are one in him. In other words, Brahman in his unity of spirit is aware of his multiplicity of souls and in the consciousness of his multiple souls is aware of the unity of all souls. In each soul he, the immanent Spirit, the Lord in each heart, is aware of his oneness. The Jivatman illumined by him, aware of its unity with the One, is also aware of its unity with the many. Our superficial consciousness, identified with body and with divided life and dividing mind, is ignorant; but that also can be illumined and made aware. Multiplicity, then is not the necessary cause of the ignorance.”
During his time in prison during the early years of the independence movement in India, Sri Aurobindo had the palpable experience of this Oneness, and he saw the tree sheltering him from the sun as Sri Krishna protecting him; he saw the judge and the prosecutor, as well as his defense attorney, as that One and he gave himself up to the protection and direction that the one Spirit in all was working out. As we know, he was eventually acquitted of all charges against him and partially as a result of the experience he had during that time, he gave up his political calling and turned to matters spiritual, which occupied the rest of his long life in Pondicherry, India.
Sri Aurobindo, The Life Divine, Book 2, Part I, Chapter 12, The Origin of the Ignorance