“Neither a borrower nor a lender be / For loan oft loses both itself and friend / And borrowing dulls the edge of husbandry.” It’s a lovely bit of verse, but Shakespeare is no financial adviser. Few people today can buy a house without a mortgage. And, until recently, even those who could were often wise to borrow the money.

For decades, mortgage-holders who invested any spare cash rather than paying off debt might in fact have been husbanding their resources rather well. Interest rates stayed low for years, and certainly much lower than the returns available on shares, whose prices soared. Now, though, as I wrote in this Buttonwood column, the arithmetic has flipped. For the first time in a while, Shakespeare’s advice is worth heeding for those who can.