When we observe the workings of Nature, we see processes that are worked out in intricate detail and which can span aeons of time in their working. Even short-lived creatures are part of a much larger fabric of life which itself spans long periods of time and which encompasses what came before and sets the stage for what comes after. We see no evidence of any caprice or happenstance in this organized rolling-out of the manifestation. It is therefore unlikely and highly suspect to assume that the Soul which we either intuit or actually experience as providing an independent actor in this development is something that suddenly appears without any precedent, or disappears without any trace after one lifetime.
Sri Aurobindo takes up this issue: “It is reasonable to suppose that this powerful independent element which supervenes and works upon the physical and vital evolution, was in the past and will be in the future. It is reasonable also to suppose that it did not come in suddenly from some unconnected existence and does not pass out after one brief intervention; its close connection with the life of the world is rather a continuation of a long past connection. And this brings in at once the whole necessity of past birth and karma. I am a persistent being who pursue my evolution within the persistent being of the world. I have evolved my human birth and I help constantly in the human evolution. I have created by my past karma my own conditions and my relations with the life of others and the general karma. That shapes my heredity, my environment, my affinities, my connections, my material, my opportunities and obstacles, a part of my predestined powers and results, not arbitrarily predestined but predetermined by my own stage of nature and past action, and on this groundwork I build new karma and farther strengthen or subtilise my power of natural being, woven in with the universal evolution and all its lines are included in the web of being, but it is not merely a jutting point or moment of it or a brief tag shot into the tissue.”
We see here a coherent and organized process that provides a clear sense of the soul’s evolutionary effort through the mechanism of karma, cause and effect, carried out through time by the operation of the systematic rebirth of the soul.