Isidore of Seville’s Etymologiae has always been a subject of interest to lawyers. This concerns in particular its chapter five: Laws and times. This article, however, points out that a different fragment of Etymologiae carries certain importance to understanding the relation between ius and lex – an excerpt from chapter twenty. Isidore of Seville analyses there also another meaning of the word ius. On this basis, this article attempts to investigate the relation between different notions of law in a philosophical and legal angle