E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Cynic Tub (The).
The tub from which Diogens lectured. Similarly we speak of the Porch, that is, the Porch Pcl, meaning Stoic philosophy; the Garden, meaning Epicuran philosophy; the Academy, meaning Platonic philosophy; the Colonnade, meaning Aristotelian philosophy.
[They] fetch their doctrines from the Cynic tub.