But to return to our chess-men. A closer study of the game would reveal--in addition to the invariable sequence of Black, White, Black--the fact that the various pieces had various properties and moved in various ways, some only one square at a time, some the whole length of the board; some diagonally, some parallel to the sides of the board. Further, our philosopher would observe that each piece when it moved tended to move according to its own laws: in the absence of counteracting causes, _e.g._ unless some other piece blocked the way, a bishop tended to move diagonally the whole length of the board. As a man of science, he would state these observed uniformities in the hypothetical form rightly adopted by science: if a castle moves it tends to move in such and such a way. Thus eventually he would be able to foretell, whenever any piece began to move, what direction it tended, in the absence of counteracting causes, to take. He might not, indeed, be able to say beforehand which of White's pieces would move in reply to Black, but his knowledge of the game would eventually become so scientific that he would be prepared for most contingencies, _i.e._ be able to say approximately where any piece would move if it did move. That knowledge could be attained without making any assumption as to whether free-will or necessity was the motive force expressed in the game; and it would be equally valid whichever of the two assumptions he chose to make. His science would have nothing to hope or fear from either assumption.