Here White’s immediate prospects for mate may look dim at first glance; of course he can check on the back rank with Re8, but then the king has unguarded flight squares on h7 and especially f7 (and then f6, etc.). But observe that moving the king to either f7 or h7 will place it in a diagonal relationship to White’s knight. This signals the possibility of the Arabian mate if White can give check with a heavy piece on a square next to the king that the knight protects—as he then can with Rf8# or Rh8# (depending which way Black’s king has fled). Notice the side features needed to make the idea work here: protection for the knight, and a pawn on g7 to constrain the king’s range of motion. Without those elements the mate fails. The pawn on h6, on the other hand, is unnecessary.