So true is this, that there is not a bill of sale, not a farm lease, not an annuity, but implies it.

I will quote only one example.
How do we measure the value of land?
By its product.

If a piece of land yields one thousand francs, we say that at five per cent.

it is worth twenty thousand francs; at four per cent.

twenty-five thousand francs, &c.; which means, in other words, that in twenty or twenty-five years' time the purchaser would recover in full the amount originally paid for the land.