be useful

References in classic literature ?
SOCRATES: And in supposing that they will be useful only if they are true guides to us of action--there we were also right?
Harriet would be loved as one to whom she could be useful.
A degree or two lower, and a creditable appearance might interest me; I might hope to be useful to their families in some way or other.
Now, when she knew better how to be useful, and how to forbear, and when her mother could be no longer occupied by the incessant demands of a house full of little children, there would be leisure and inclination for every comfort, and they should soon be what mother and daughter ought to be to each other.
I now began to consider that I might yet get a great many things out of the ship which would be useful to me, and particularly some of the rigging and sails, and such other things as might come to land; and I resolved to make another voyage on board the vessel, if possible.
I was a little surprised, but recovered myself with the satisfactory reflection that I had lost no time, nor abated any diligence, to get everything out of her that could be useful to me; and that, indeed, there was little left in her that I was able to bring away, if I had had more time.
But, it being my intention to write a thing which shall be useful to him who apprehends it, it appears to me more appropriate to follow up the real truth of the matter than the imagination of it; for many have pictured republics and principalities which in fact have never been known or seen, because how one lives is so far distant from how one ought to live, that he who neglects what is done for what ought to be done, sooner effects his ruin than his preservation; for a man who wishes to act entirely up to his professions of virtue soon meets with what destroys him among so much that is evil.
If what the nigger said was in any wise true, the man had a rare gift which might be useful in the quest they were after.
The 42-year-old hopes she will be useful to co-star Tess Daly, who is replacing Bruce Forsyth when the BBC1 hit returns in September.
Immunohistochemical detection of rickettsial antigens may be useful in diagnosing ATBF.
I do think that it is good for you (readers and authors) to have a little better idea of what you are getting with a new editor, and, as a counselor, I do think that a little appropriate disclosure can be useful.
Here it might be useful to compare Noguchi's "design" work with that contemporaneously produced by Charles and Ray Eames for Herman Miller.