Rhetoric, Lect. xx, p. 200.  Now the facts are these:  (1.) That that is the more definitive or restrictive word of the two. (2.) That the word which has as many different senses and uses as the word that. (3.) That not the repetition of which or who in a series of clauses, but a needless change of the relative, is ungraceful. (4.) That the necessity of using that rather than which or who, depends, not upon what is here supposed, but upon the different senses which these words usually convey. (5.) That as there is always some reason of choice, that is sometimes to be preferred; which, sometimes; and who, sometimes:  as, “It is not the man who has merely taught, or who has taught long, or who is able to point out defects in authors, that is capable of enlightening the world in the respective sciences which have engaged his attention; but the man who has taught well.”—­Kirkham’s Elocution, p. 7.

OBS. 33.—­Blair’s Rhetoric consists of forty-seven lectures; four of which are devoted to a critical examination of the style of Addison, as exhibited in four successive papers of the Spectator.  The remarks of the professor are in general judicious; but, seeing his work is made a common textbook for students of “Belles Lettres,” it is a pity to find it so liable to reprehension on the score of inaccuracy.  Among the passages which are criticised in the twenty-first lecture, there is one in which the essayist speaks of the effects of novelty as follows: 

’It is this which bestows charms on a monster, and makes even the imperfections of nature please us.  It is this that recommends variety, where the mind is every instant called off to something new, and the attention not suffered to dwell too long and waste itself on any particular object.  It is this, likewise, that improves what is great or beautiful, and makes it afford the mind a double entertainment.’—­Spectator, No. 412.

This passage is deservedly praised by the critic, for its “perspicuity, grace, and harmony;” but, in using different relatives under like circumstances, the writer has hardly done justice to his own good taste.  Blair’s remark is this:  “His frequent use of that, instead of which, is another peculiarity of his style; but, on this occasion in particular, [it] cannot be much commended, as, ‘It is this which,’ seems, in every view, to be better than, ‘It is this that,’ three times repeated.”—­Lect. xxi, p. 207.  What is here meant by “every view,” may, I suppose, be seen in the corresponding criticism which is noticed in my last observation above; and I am greatly deceived, if, in this instance also, the relative that is not better than which, and more agreeable to polite usage.  The direct relative which corresponds to the introductory