But this theory of Transmigration, as described by Plato, is a little different from a similar theory which existed in India before his time. In the Platonic idea of transmigration, as we have already seen, the souls were allowed to choose their own lot according to their experience or bent of character, but not to receive the natural consequence of their deeds and misdeeds. Plato did not say anything about the law which governs souls; but in ancient India the great thinkers and philosophers explained that each individual soul is bound by the inexorable law of nature to receive its body as a natural consequence of its former deeds and misdeeds, and not to have free choice of its lot according to its bent of character. The great thinkers and philosophers of ancient India discovered the universal law of cause and effect, of action and reaction, and called it by the Sanskrit term "Karma," which means the law of cause and sequence; that every cause must be followed by an effect of a similar nature, that every action must produce similar reaction, and conversely every reaction or effect is the result of an action or cause of a similar character. Thus there is always a balance and harmony between cause and effect, between action and reaction. This law of Karma has now become a fundamental verity of modern science. It is called by different names: the scientists call it the law of causation, the law of compensation, the law of retribution, the law of action and reaction, but they all refer to the same idea,--that every cause must produce a similar result and every action must produce a similar reaction.