In the Advocates' Library at Edinburgh, of which Scott was in 1795 appointed a curator, was an important manuscript that contained among other metrical romances one professing to be a copy of that written by Thomas of Erceldoune on Sir Tristrem.

From a careful piecing together of evidence furnished by this poem and by Robert of Brunne, with the assistance of certain legal documents which supplied dates, Scott built up about the old poet a theory that he elaborated in his edition of _Sir Tristrem_, published in 1804, and that continued to interest him vividly as long as he lived.

It reappears in many of his critical writings[78] and also in the novels.

In the _Bride of Lammermoor_ Ravenswood goes to his death in compliance with the prophecy of Thomas quoted by the superstitious Caleb Balderstone.

And in _Castle Dangerous_ Bertram, who is unconvincing perhaps because he is endowed with the literary and antiquarian tastes of a Walter Scott himself, is actuated by an irrepressible desire to discover works of the Rhymer.
Scott's edition of _Sir Tristrem_ gives--besides the text, introduction, and notes--a short conclusion written by himself in imitation of the original poet's style.