Elementum in its singular form directs attention to the single fundamental constituent, while in the plural (elementa) it refers to the system of four elements as a whole. The Latin word is itself interesting etymologically: it may derive from the sequence of
letters L, M, N in the alphabet — the elementary letters — suggesting that the elements are the ABC of material reality, the most basic units from which everything else is built. Students should note that
the four elements have different poetic
associations and symbolic valences: earth (stability, body,
mortality, fertility); water (time, emotion, the
unconscious, transformation); fire (spirit,
destruction, purification, inspiration); air (
intellect, freedom, inspiration, the immaterial). These associations have been remarkably stable across Western culture and continue to provide the basic vocabulary of nature
imagery in poetry. Related terms include the humours (blood, phlegm, yellow bile, black bile), which were the physiological equivalents of the four elements in medical theory.