“A shoe or boot, anything adapted to cover and preserve the feet in walking. The use of shoes was by no means universal amount the Greeks and Romans. The Homeric heroes are represented without shoes when armed for battle. Socrates, Phocion, and Cato, frequently went barefoot. The Roman slaves had no shoes. the covering of the feet was removed before reclining at meals. People in grief, as for instance at funerals, frequently went barefooted. Shoes may be divided into those in which the mere sole of a shoe was attached to the sole of the foot by ties or bands, or by a covering for the toes or the instep; and those which ascended hgher and higher, according as they covered the ankles, the calf, or the whole of the leg. To calceamenta of the latter kind, i.e. to shoes and boots, as distinguished from sandals and slippers, the term calceus was applied in its proper and restricted sense.” — Smith, 1873; This image shows Calceus, Men’s Shoes.
William Smith, A School Dictionary of Greek and Roman Antiquities (New York: Harper and Brothers, 1873) 57