The Knight.
Here are four Knights on the board, and a Rook and a Bishop and the two Kings. Two of the Knights are immobile, Knight e2 on account of the Bishop h5 and the Knight g7 because of the Rook g3: they must protect their Kings. The Knight f5 can move to one of the following squares: e7, d6, d4, e3, g3 (whereby it captures the Rook) h4, h6. The shortest jump on the Chess-board is, namely, to take two squares (in the air) in a line or row and one square perpendicularly thereto. That movement allows to Knight f5 eight possibilities, but in the above position one of these, on the square g7, is taken away by the obstruction of a X partisan to Knight f5. The Knight f6 has eight possible moves: it threatens the hostile King, "gives Check," "Checks," and the King will have to fly, for instance, to f7, in order to save himself.