described before; so that to speak of doing this or thus, is merely the shortest way of repeating the idea:  as, “He loves not plays, as thou dost.  Antony.”—­Shak. That is, “as thou dost love plays.” “This fellow is wise enough to play the fool; and, to do that well, craves a kind of wit.”—­Id. Here, “to do that,” is, “to play the fool.”  “I will not do it, if I find thirty there.”—­Gen., xviii, 30.  Do what?  Destroy the city, as had been threatened.  Where do is an auxiliary, there is no real substitution; and, in the other instances, it is not properly the verb do, that is the substitute, but rather the word that follows it—­or perhaps, both.  For, since every action consists in doing something or in doing somehow, this general verb do, with this, that, it, thus, or so, to identify the action, may assume the import of many a longer phrase.  But care must be taken not to substitute this verb for any term to which it is not equivalent; as, “The a is certainly to be sounded as the English do.”—­Walker’s Dict., w.  A.  Say, “as the English sound it;” for do is here absurd, and grossly solecistical.  “The duke had not behaved with that loyalty with which he ought to have done.”—­Lowth’s Gram., p. 111; Murray’s, i, 212; Churchill’s, 355; Fisk’s, 137; Ingersoll’s, 269.  Say, “with which he ought to have behaved;” for, to have done with loyalty is not what was meant—­far from it.  Clarendon wrote the text thus:  “The Duke had not behaved with that loyalty, as he ought to have done.”  This should have been corrected, not by changing "as" to "with which", but by saying—­“with that loyalty which he ought to have observed;" or, “which would have become him".

OBS. 19.—­It is little to the credit of our grammarians, to find so many of them thus concurring in the same obvious error, and even making bad English worse.  The very examples which have hitherto been given to prove that do may be a substitute for other verbs, are none of them in point, and all of them have been constantly and shamefully misinterpreted. Thus:  “They [do and did] sometimes also supply the place of another verb, and make the repetition of it, in the same or a subsequent sentence, unnecessary:  as, ‘You attend not to your studies as he does;’ (i. e. as he attends, &c.) ’I shall come if I can; but if I do not, please to excuse me;’ (i. e. if I come not.)”—­L.  Murray’s Gram., Vol. i, p. 88; R.  C. Smith’s, 88; Ingersoll’s, 135; Fisk’s, 78; A.  Flint’s, 41; Hiley’s, 30.  This remark, but not the examples, was taken from Lowths Gram., p. 41.  Churchill varies it thus, and retains Lowth’s example:  “It [i. e., do] is used