His own experience of the small room that ardor can make for itself in ordinary minds had had the effect of increasing his reserve; and while tolerance was the easiest attitude to him, there was another bent in him also capable of becoming a weakness--the dislike to appear exceptional or to risk an ineffective insistence on his own opinion. 
He had experience of the small space that ardour finds in ordinary minds; and this had resulted in a reserve - a dislike of appearing unusual or of risking an ineffective insistence on his own opinion. 