"Best Rejection Letter Ever":

...it is with no inconsiderable degree of reluctance that I decline the offer of any Paper from you. I think, however, you will under reconsideration of the subject be of the opinion that I have no other alternative. The subjects you propose for a series of Mathematical and Metaphysical Essays are so very profound, that there is perhaps not a single subscriber to our Journal who could follow them.

Sir David Brewster editor of The Edinburgh Journal of Science to Charles Babbage on July 3, 1821.