Here's a great sympathy quote from Zarlino [1556] for anyone writing a dissertation:

"...everyone, inasmuch as he is human, may be mistaken in his opinion.  And let us remember what Horace writes in the Epistle of Ars poetica:

Verum opere in longo obrepere somnum.
[Truly in a long work it is natural for sleep to creep up.]

This could be an excellent excuse for this most serious author, and also for everyone else who writes at great length."