Closely following comparative grammar, almost at the same time rose up comparative mythology, and with the ancient words awoke the gods that they had sung, the beliefs that they had fostered. It was recognized that if the Indo-Europeans spoke essentially the same language, they also worshipped essentially the same gods and believed in the same things. As comparative grammar, on hearing the sister-tongues, caught up the echo of the mother, whose voice they repeat, so comparative mythology, in its turn, on looking at the sister religions, has tried to see through them the original image which they reflect. As the one restored the words and forms of the language which lived on the lips of the Aryans at the moment of the breaking up of the Aryan unity, the other endeavoured to restore the gods and beliefs which lived in their souls at the moment when, with the unity of the race, the identity of language and belief passed away. This restoration of the pre-historic gods and of the pre-historic beliefs is the final object of comparative mythology, just as the reconstruction of words and forms is the final object of comparative grammar. The object was analogous and so was the method. It is the comparative method, which by comparing kindred divinities and kindred beliefs, finds the original divinity and the original belief which gave birth to them, and which are reproduced in them. To sketch the picture of the original mythology, it is sufficient to separate from the various derivative mythologies the essential characteristics common to them. Every characteristic common to the secondary religions will be legitimately referred to the primitive one, whenever it is essential--that is to say neither borrowed from one of the kindred religions nor due to an identical, but quite independent development. If, for instance, the various Indo-European mythologies agree in naming the gods _Daiva_, "the shining ones," it follows that in the primitive mythology, in the religion of the period of unity, they were known already as beings of light and called thus. It is a great deal easier to admit that the seven derived religions have faithfully repeated what has been handed down to them from their common source, than to imagine that once separated they have created the same conception, each one on its side, and have clothed it with the same expression: the former hypothesis is a simple and natural induction: the second is in reality made up of seven hypotheses, and implies seven chances agreeing together, seven miracles. Our object in the following pages is to give a sketch of one of the chapters of the Aryan mythology. We try to show that the religion of the Indo-European unity recognized a Supreme God, and we try to find the most ancient form and the earliest origin of that conception among the Aryans, and to follow out the transformations it has undergone in the course of ages. The Supreme God: Zeus, Jupiter, Varuna, Ahura Mazda.