It was the critic Alexander who put me on my guard against unnecessary fault-finding. People should not be sharply corrected for bad grammar, provincialisms, or mispronunciation; it is better to suggest the proper expression by tactfully introducing it oneself in, say, one’s reply to a question or one’s acquiescence in their sentiments, or into a friendly discussion of the topic itself (not of the diction), or by some other suitable form of reminder.
