I recd. in due time your favor of the 21. Ult: and have looked over the lucubrations of Regulus now returned to your files; but with an attention less close than the subject of them would require. I concur entirely in the distinction made between the authority of a Constitution, and that of public opinion. The former is the record of the national Will, and no evidence however specious or true can prevail against it. In the cases which have occurred, particularly that to which my remarks related, the question was not between the Constitution and the public opinion, but between different interpretations of the Instrument, all admitting that to be the paramount authority, and claiming it for themselves in its true meaning. Unhappily this must often be more or less the case. The imperfection of language, especially when terms are to be used, the precise import of which has not been settled by a long course of application, is one cause. The change which the meaning of words inadvertently undergoes, examples of which are already furnished by the Constitution of the U. S., is another. And more frequent & formidable than either cause, is the spirit of party or the temptations of interest. Nor is the public good real or supposed, without occasional effect in betraying honest minds, into misconstructions of the Constitutional text. These are evils which can not be altogether avoided, but they are not to be compared with those inherent in arbitrary and undefined forms of Government. They are too, such as time, usage, and the gradual incorporation of the vital maxims of free Government into the national sentiment, must tend to diminish.

My suggestion as to the different course proper to be pursued in opposing measures of the Federal Government, as they have or have not the support of the States and of the people, was founded on prudential considerations only. The language of menace & defiance, when addressed to those who have force, and think they have right also, on their side, defeats itself: It sometimes does more, it is known to excite derision when proceeding from the Southern quarter, which has such peculiar reasons for distrusting its inherent strength. A defying tone of opposition should never be indulged till every other experiment has failed; nor then, but on occasions, justifying the last resort, however hazardous, of an oppressed people.

I foresee much difficulty and some danger of a protracted vacancy, in providing a Successor to Mr. Key. The expediency of calling Mr. Gallatin to our aid had occurred to me. I have great confidence in his judgment and his readiness to employ it for our purpose. But his intercourse with the Scientific World is probably much less in England, than it has been in France, where it would not be our choice to look for a supply of our wants. Tho’ abounding more than England in Scientific candidates, these, to say nothing of the difference of language, would not assort so well with their American Colleagues: and much less perhaps with their English ones, in the University. It would not be prudent however to shut the door absolutely agst. the French resource. Pre-eminent Science, and personal dispositions & habits, may outweigh the objections to it. If Mr. Key persists in his intention to leave us, a few days may be expected to bring us his notification to that effect.

I need not I hope remind you that it is no longer Winter and that the roads will not be long an objection to the excursion promised us by Mrs. Trist & yourself. With affectionate respects

We hope you continue to have favorable accounts from Boston, & from all other quarters.