Francis P. Siegfried, Catholic Encyclopedia (1913)
“ These three groups are called intrinsic accidents, to distinguish them from the remaining six groups—action, passion, location, duration, position, habiliment—which, as their names sufficiently suggest, are simply extrinsic denominations accruing to a substance because of its bearings on some other substance. Quantity and quality, and, in a restricted sense, relation are said to be absolute accidents, because they are held to superadd some special form of being to the substance wherein they reside. ”
