Tenui musam metitamur avena

Or, "We cultivate literature on a little oatmeal." Ref. in Richardson's biography of William James, p.59. Coined by Sydney Smith, a founding editor of The Edinburgh Review. 

From Richardson:

"Smith was an ardent believer in the association of ideas, in the notion, first given its full form by David Hartley, that "complex mental phenomena are formed from simple elements derived ultimately from sensation." The belief that everything mental has a physical explanation and origin--one of the rocks on which positivism is built--is put forward by Smith by way of an attack on metaphysics, " word of dire sound and horrible import," says Smith. "A great philosopher," he says, "may sit in his study and deny the existence of matter: but if he takes a walk in the street he must take care to leave his theory behind him."