And according to Caeneus [Speusippus] was the first to divulge what Isocrates called the secrets of his art, and the first to devise the means by which fagots of firewood are rendered portable.
When he was already crippled by paralysis, he sent a message to Xenocrates entreating him to come and take over the charge of the school. They say that, as he was being conveyed to the Academy in a tiny carriage, he met and saluted Diogenes, who replied, “Nay, if you can endure to live in such a plight as this, I decline to return your greeting.” At last in old age he became so despondent that he put an end to his life. Here follows my epigram upon him: Had I not learnt that Speusippus would die thus, no one would have persuaded me to say that he was surely not of Plato's blood; for else he would never have died in despair for a trivial cause.
Source: Lives of the Eminent Philosophers (1925) by Diogenes Laërtius, translated by Robert Drew Hicks