What is the test for admissible evidence in a promissory note case?

Solomon v. Turner (1815), 1 Stark. 51 at p. 52, 171 E.R. 398 at p. 399, is more general. The allegation was that the pictures which constituted the consideration for the promissory note were worth much less than their purchase price. Lord Ellenborough, C.J., said: I will not admit the evidence for the purpose of reducing the damages by shewing that the pictures were of an inferior value, but if you can, by the inadequacy of the value and other circumstances, prove fraud on the part of the plaintiff, so as to shew that there was no contract at all, the evidence will be admissible; if it fall short of that, it will be unavailable.