Speaking of and praising the Ravenna chair, Passeri offers some very useful remarks by way of caution against the hasty conclusions which some make, who set down all ancient large plaques of ivory as having been the leaves of diptychs: “Vidi etiam Ravennæ in chartophilacio principis ecclesiæ sedem eburneam sancti Maximiani episcopi quinto seculo operosissime efformatam, cujus ambitum undequaque adornant tabulæ eburneæ amplitudinis fere sesquipedalis, quam plerumque ebur patitur anaglypho opere, et scitissima manu elaboratæ, quæ si disjectæ et singulares occurrent imprudentibus facile imponerent, ut inter diptycha censerentur. Nec ista nominis quæstio est, nam longe alia mente explicandæ sunt missiles consulum tabellæ, atque in illis expressa emblemata, quæ omnia ad consulatum ejusque pompas pertinent, alia vero sculpturæ omnes, quæ in alium usum parabantur. Hæc observatio facile prodit errorem illorum, qui diptychis adcensuerunt laterculos, nullo consule designatos, cum musarum, poetarum, Bacchantum ac deorum imaginibus, quæ mihi nullam aliam ingerunt speciem, quam quod aliquando libros contexerint, quibus parerga adluderent. Sunt præterea quædam imperatorum inferioris ævi simulacra tabellis eburneis incisa, in quibus nulla cardinum vestigia apparent, ut potius videatur sedes honorarias decorasse, quam quod diptychorum loco essent, quum præsertim exterior illorum ornatus superne in acutum desinat; quod a diptychorum instituto quam maxime abhorret.” CHAPTER V. About the time when the chair of Ravenna was made, that is, in the sixth century, sculpture in ivory again sensibly declined. The figures in Byzantine work of that period begin to be characterised by sharpness and meagreness of form, and lengthiness of proportion; in the heads, however, we yet find a good expression; and especially in representations of our Lord dignity and resignation. The costume also gradually became more and more covered with ornaments and jewels; although the ancient classical robes were still copied, and apostles were clothed in togas, or the virgin in a chlamys and tunic, or the magi in Phrygian caps.