Bacon presents a detailed classification of signs[24] by taking up, combining, and modifying elements of several prior sign typologies. The division of the two main classes of natural and given signs is taken from Augustine, the distinction between necessary and probable signs is borrowed from Aristotle (an. pr. II, 27, 70a3-b5), and their subdivision according to their temporal reference is a traditional element in the theories of the sacramental sign.[25] 1. NATURAL SIGNS 1.1 signifying by inference, concomitance, consequence 1.1.1 signifying necessarily 1.1.1.1 signifying something present (large extremeties → strength) 1.1.1.2 signifying something past (lactation → birth of a child) 1.1.1.3 signifying something future (dawn → imminent sunrise) 1.1.2 signifying with probability 1.1.2.1 signifying sth. present (to be a mother → love) 1.1.2.2 signifying sth. past (wet ground → previous rain) 1.1.2.3 signifying sth. future (red sky in the morning → rain) 1.2 signifying by configuration and likeness (images, pictures, species of colour) 1.3 signifying by causality (tracks → animal) 2. SIGNS GIVEN AND DIRECTED BY A SOUL 2.1 signifying instinctively without deliberation (sigh → pain; laughter → joy) 2.2 signifying with deliberation (words) 2.3 interjections