Are there any arguments, any rational proofs for this reincarnation of the soul? So far we have been giving the negative side, showing that the opposite arguments to disprove it are not valid. Are there any positive proofs? There are; and most valid ones, too. No other theory except that of reincarnation accounts for the wide divergence that we find between man and man in their powers to acquire knowledge. First, let us consider the process by means of which knowledge is acquired. Suppose I go into the street and see a dog. How do I know it is a dog? I refer it to my mind, and in my mind are groups of all my past experiences, arranged and pigeon-holed, as it were. As soon as a new impression comes, I take it up and refer it to some of the old pigeon-holes, and as soon as I find a group of the same impressions already existing, I place it in that group, and I am satisfied. I know it is a dog, because it coincides with the impressions already there. When I do not find the cognates of this new experience inside, I become dissatisfied. When, not finding the cognates of an impression, we become dissatisfied, this state of the mind is called "ignorance"; but, when, finding the cognates of an impression already existing, we become satisfied, this is called "knowledge". When one apple fell, men became dissatisfied. Then gradually they found out the group.