Francois-Andre Danican Philidor quotes:

The Pawns are the soul of the game

Pawns: they are the soul of this game, they alone form the attack and defense

The pawn is the soul of chess.

A pawn, when separated from his fellows, will seldom or never make a fortune.

It is always advantageous to exchange your king's bishop pawn for the king's pawn, since this leads to the seizure of the centre and, in addition, to the opening of a file for the rook.