Diogenes received an invitation to dine with one whose house was splendidly furnished, in the highest order and taste, and nothing therein wanting. Diogenes, hawking, and as if about to spit, looked in all directions, and finding nothing adapted thereto, spat right in the face of the master. He, indignant, asked why he did so? "Because," Diogenes, "I saw nothing so dirty and filthy in all your house. For the walls were covered with pictures, the floors of the most precious tessellated character — and ranged with the various images of gods, and other ornamental figures."
Galen, Exhortation to Study the Arts, Coxe (1846), p. 479; cf. Diogenes Laërtius, vi. 32.