Here, after 1. P to K 4, P to K 4; 2. Kt to K B 3, Black, instead of
defending the K P with 2. ... Kt to Q B 3, plays Kt to K B 3, attacking the
opponent's K P. This mode of defence is sometimes adopted if the second
player wishes to avoid the Ruy Lopez, Scotch Opening, or Evans Gambit. On
the whole it yields a safe defence, although somewhat tame in the majority
of variations.