Beethoven’s 10th. Tchaikovsky’s 7th. Elgar’s 3rd. The path to classical music glory is strewn with completions of unfinished symphonies. Very few of these completions actually work.

I can understand the temptation to bring to light a lost symphony by a beloved master. What I wouldn’t give to hear Sibelius’ 8th, as the composer intended. (Alas, his grandson told me he was in the room when the manuscript was tossed into the fire.) However, as a rule, it is more prudent in these matters to emulate Odysseus and stop our ears, lest we be dashed against the rocks and our vessels shattered to pieces.

For all the joy and affirmation our favorite composers have given us, the dignity of eternal rest is the least we owe them. Let the scholars pore over the unfinished manuscripts, by all means issue recordings for the curious, but please don’t act like your Frankenstein is canon.

One of the few completions that seems to have actually been accepted, in some circles, is Deryck Cooke’s of Mahler’s Symphony No. 10. Previously known only for its devastating Adagio – which, if I’m to opine, is perfectly satisfying in itself – Cooke’s edition is an intriguing realization of Mahler’s sketches. Of course, the symphony, as I understand it, was near completion at the time of Mahler’s death, albeit in a very rough form, and only the first movement had been orchestrated.

Mahler finished nine symphonies in full score. The story goes that he deliberately avoided designating “Das Lied von der Erde” a symphony, coming as it did on the heels of his Symphony No. 8, in order to sidestep the “Curse of the Ninth.” Beethoven, Schubert, Bruckner, Dvorak and too many others all died following the completion of their ninth symphonies. “Das Lied” was, in effect, a stay of execution. But, like something out of the “Final Destination” series, with his next numbered symphony, sure enough, the Reaper found him out.

Observed Arnold Schoenberg, “It seems that the Ninth is a limit. He who wants to go beyond it must pass away. It seems as if something might be imparted to us in the Tenth, for which we are not ready.”

The reason I mention it at all is because today would have been Deryck Cooke’s 100th birthday. Others have tried their hands at completing Mahler’s 10th – Cooke himself would have been the first to admit his was not the last word on the subject (over the years, he revised his thoughts at least three times) – but his is the one that seems to have retained the widest currency.

Early in his career, Cooke himself was a composer. He later became a respected musicologist and broadcaster for the BBC.

Bruno Walter, Leonard Bernstein, Rafael Kubelik, and Pierre Boulez all rejected the idea of a completed Mahler 10th. Schoenberg, Shostakovich, and Britten refused to have a hand in its completion. Personally, I can’t come to accept the piece as canon, but with 19 recordings in the current catalogue, it looks as if it’s here to stay.

Happy birthday, Deryck Cooke.