François-André Danican Philidor (1726-1795) was ahead of his time in positional understanding. He also had strong views concerning the rules of chess at a time while there were still local variations. In parts of Germany, for instance, Philidor reports that the en passant capture was not observed. He expressed his outrage with a clear statement concerning the necessity for the en passant rule once pawns were given the power of advancing two squares on their initial move.
[T]hey give a pawn leave to pass beyond taking by Pawns; which not only makes quite a different Game from the original one, but also takes off a great deal of its Beauty; because by this means a Pawn may pass before two others, who with much Dexterity and Industry have reached within three Squares of becoming Queens, and are there stopt by the King, or the Adversary's Bishop; while this single Pawn will either go and make a Queen, or oblige you to abandon all your advanced Pawns and come attack this Wretch, who during the whole Game has done nothing. This certainly is quite opposite to the Rules of war, where Merit only can advance a Soldier's Fortune.It would be much better to let one of the worthy pawns who has labored throughout the course of the battle to strike down the lazy upstart. For this reason, Philidor seems to say, we permit capturing a pawn en passant. It is a good rule that ought to be observed everywhere.
Philidor, Chess Analysed (London, 1750), vi-vii.