WHICH RELATIVE PRONOUN TO USE

373. We are sometimes confused as to which relative pronoun to use in introducing an adjective clause. We hesitate as to whether we should use that or who or which. Remember that who always refers to persons, which refers to animals or things, and that may refer to either persons, animals or things.

So when referring to a person, we may use either who or that, and when referring to animals or things, we may use either which or that. As, for example, we may say, either, The man who was here yesterday came back today, or The man that was here yesterday came back today. Either is correct, for who and that both refer to persons.

374. We may make a little distinction in the use of who and that when referring to persons, however. A clause introduced by that is usually a restrictive clause. It limits or restricts the meaning of the noun which it modifies. When you say, The man that was here yesterday, you mean that man and no other, limiting your meaning to that particular man. On the other hand, when you say, The man who was here yesterday, there is no restriction or limitation expressed in the use of the clause, but it is merely a descriptive clause, adding a new fact to our knowledge concerning that particular man.

The same is true when we are speaking of things using either that or which. The clause introduced by which is presumably a descriptive clause. We do, however, often use who or which when the sense of the clause is restrictive, but we should never use that to introduce an adjective clause, unless the sense is restrictive. When in your sentences you can use, instead of the relative pronoun who or which, the conjunction and, you can know that the use of the pronoun who or which is correct. As, for example:

You could say instead:

This would express the same meaning. But if you say: I have read the book that I found very interesting, you mean that you limit your idea to this particular book.

375. We do not always observe these niceties in our spoken and written speech, but it is interesting to know the shades of thought and meaning which you can express by the proper use of the language. The man who runs an engine and learns to know and love his machine almost as though it were a human being, can easily recognize the slightest change in the action of his machine. His ear catches the least difference in the sound of the running of the machine, a difference which we, who do not know and love the machine, would never notice.

So it is in language. Once we have sensed its beauty and its wondrous power of expression, we notice all these slight differences and shades of meaning which may be expressed by the use of words. In just the same manner the musician catches the undertones and overtones of the music, which we, who possess an uneducated ear, cannot know; and the artist also has a wondrous range of color, while we, who are not sensitive to color, know only a few of the primal colors.