Donal desired to be useful and live for his generation, also to be with books.

To be where was a good library would suit him better than buying books, for without a place in which to keep them, they are among the impedimenta of life.
And Donal knew that in regard to books he was in danger of loving after the fashion of this world: books he had a strong inclination to accumulate and hoard; therefore the use of a library was better than the means of buying them.

Books as possessions are also of the things that pass and perish--as surely as any other form of earthly having; they are of the playthings God lets men have that they may learn to distinguish between apparent and real possession: if having will not teach them, loss may.
But who would have thought, meeting the youth as he walked the road with shoeless feet, that he sought the harbour of a great library in some old house, so as day after day to feast on the thoughts of men who had gone before him! For his was no antiquarian soul; it was a soul hungry after life, not after the mummy cloths enwrapping the dead..