The English speaking world may be divided into (1) those who neither know nor care what a split infinitive is; (2) those who do not know, but care very much; (3) those who know and condemn; (4) those who know and approve; and (5) those who know and distinguish. Those who neither know nor care are the vast majority and are a happy folk, to be envied by most of the minority classes.

Modern English Usage (1926)