There are also cases where we are able to perceive the reasons which inspired this. The two phratries were very probably the original and fundamental bases for these classifications, which were consequently bifurcate at first. Now, when a classification is reduced to two classes, these are almost necessarily conceived as antitheses; they are used primarily as a means of clearly separating things between which there is a very marked contrast. Some are set at the right, the others at the left. As a matter of fact this is the character of the Australian classifications. If the white cockatoo is in one phratry, the black one is in the other; if the sun is on one side, the moon and the stars of night are on the opposite side.[444] Very frequently the beings which serve as the totems of the two phratries have contrary colours.[445] These oppositions are even met with outside of Australia. Where one of the phratries is disposed to peace, the other is disposed to war;[446] if one has water as its totem, the other has earth.[447] This is undoubtedly the explanation of why the two phratries have frequently been thought of as naturally antagonistic to one another. They say that there is a sort of rivalry or even a constitutional hostility between them.[448] This opposition of things has extended itself to persons; the logical contrast has begotten a sort of social conflict.[449] It is also to be observed that within each phratry, those things have been placed in a single clan which seem to have the greatest affinity with that serving as totem. For example, the moon has been placed with the black cockatoo, but the sun, together with the atmosphere and the wind, with the white cockatoo. Or again, to a totemic animal has been united all that serves him as food,[450] as well as the animals with which he has the closest connection.[451] Of course, we cannot always understand the obscure psychology which has caused many of these connections and distinctions, but the preceding examples are enough to show that a certain intuition of the resemblances and differences presented by things has played an important part in the genesis of these classifications.