In both cases, debt was originally the exclusive action for the recovery of the amount due.

In neither case was the duty to pay conceived of as arising from a contract in the modern sense of the term.

Debt for goods sold was a grant.

Debt for rent was a reservation.

About the middle of the sixteenth century Assumpsit was allowed upon an express promise to pay a precedent debt for goods sold; and in 1602 it was decided by Slade's case that the buyer's words s of agreement, which had before operated only as a grant, imported also a promise, so that the seller might, without more, sue in Debt or Assumpsit, at his option.