Neither a borrower nor a lender be
Polonius:Hamlet Act 1, scene 3, 75–77
Neither a borrower nor a lender be,
For loan oft loses both itself and friend,
And borrowing dulls the edge of husbandry.
Old Polonius counsels his hotheaded son Laertes, who is about to embark for Paris for his gentleman's education [see THE PRIMROSE PATH]. While he still has the chance, Polonius wholesales a stockroom of aphorisms, the most famous of which is "Neither a borrower nor a lender be."
On Polonius's terms, there is little to argue with in his perhaps ungenerous advice. His logic is thus: lending money to friends is risky, because hitching debt onto personal relationships can cause resentment and, in the case of default, loses the lender both his money and his friend. Borrowing invites more private dangers: it supplants domestic thrift ("husbandry")—in Polonius's eyes, an important gentlemanly value.
Incidentally, in the days when Hamlet was first staged, borrowing was epidemic among the gentry, who sometimes neglected husbandry to the point where they were selling off their estates piece by piece to maintain an ostentatious lifestyle in London.