White has no checks that are immediately productive (though Ne7+ is not bad), so he looks for any Black pieces that might be loose. There is one: the bishop on h6. He has no direct way to attack it, but since a loose enemy piece is a big opportunity White considers whether he might build a double attack against it. Look for a visual pattern: the bishop is on the same rank as the Black queen. If the pieces between them could be cleared out of the way, White would have a fork with Rc6; the rook would be protected from QxR by the pawn on d5. Of the two men in the way, White can control its own—the knight at c6. Where can it move, and with what results? The only capture it can make is NxN. Black would reply d6xN; the pawn gets pulled off the sixth rank. Now the way is clear for Rc6, forking bishop and queen and thus winning a piece. The initial capturing sequence here illustrates a pattern of general interest: when two pieces need to be cleared off of a path, sometimes moving one of them also can force away the other.