the causa finalis for which, inversely, the future— namely, a definite goal—serves as the premise from which there can be deduced the development of the processes which lead to this goal. So long as we confine ourselves to the realm of physics, these alternative points of view are merely different mathematical expressions for one and the same fact, and it would be futile to ask which of the ewo came nearer to the truth, The choice between them depends solely on practical considerations, The chief advantage of the least- action principle is that it requires no definite frame of reference for its formulation. This prin- ‘ciple is therefore excellently adapted for carrying through transformation of coordinates. But we are now interested in questions of a ‘more general character. It will suffice at this point to note only chat the historical development of theoretic research in physics has led in a remark- able way to a formulation of the principle of physical causality which possesses an explicitly teleological character; but at the same time this formulation introduces nothing substantially new or even contradictory into the character of the Jaws of nature. The issue is simply one of different