Mr. Dickinson's Farmer's Letters were widely read and highly commended. The argument, subtle but clear, deriving the nature of an act from the intention of its makers, and the intention of its makers from the nature of the act, contributed more than any other exposition to convince Americans that they "have the same right that all states have, of judging when their privileges are invaded." "As much dependent on Great Britain as one perfectly free people can be on another," the Farmer said. Englishmen might be excused for desiring a more precise delimitation of parliamentary jurisdiction than could be found in this phrase, as well as for asking what clear legal ground there was for making any delimitation at all. To the first point, Mr. Dickinson said in effect that Parliament had not the right to tax the colonies and that it had not the right to abolish their assemblies through which they alone could tax themselves. The second point Mr. Dickinson did not clearly answer, although it was undoubtedly most fundamental. To this point Mr. Samuel Adams had given much thought; and in letters which he drafted for the Massachusetts Assembly, in the famous circular letter particularly, and in the letter of January 12, 1769, sent to the Assembly's agent in England, Mr. Dennys De Berdt, Mr. Adams formulated a theory designed to show that the colonies were "subordinate" but not subject to the British Parliament. The delimitation of colonial and parliamentary jurisdictions Mr. Adams achieved by subordinating all legislative authority to an authority higher than any positive law, an authority deriving its sanction from the fixed and universal law of nature. This higher authority, which no legislature could "overleap without destroying its own foundation," was the British Constitution.