An Old Rejection Letter

I don't suppose there are many rejection letters that most writers would want to hang on to, but this from June 2 1971 (which I only found again a few days ago) meant a lot to me at the time - and still does. It was from August Derleth, written less than a month before his death on the 4th July 1971. I wonder how many editors of his standing would have spared the time to write a detailed rejection letter like this? At the time, unsure how reliable airmail letters were and whether a submission to the great Arkham House would even get read and, more importantly, at a time before word processors had been invented and every typescript had to be individually typed , I was wary of sending my very best stories off into what might have been a void. I was ready to send off something better next time after receiving this letter, but it was too late.
 
Mind you, I did learn an important lesson from this letter and I never again used Lovecraftian names with such careless ease! And not at all for many years.