“Neither Dirk Hatteraick nor any of his sailors, all well known men
in the fair trade, were again seen upon that coast.” —
Latterly the phrase has been introduced into politics to signify reciprocity of protection or free-trade. That is, free-trade to those nations that grant free-trade to us, and vice versa.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894