1570s, from Latin evocationem (nominative evocatio) "a calling forth, a calling from concealment," noun of action from past participle stem of evocare "call out, summon; call forth, rouse, appeal to," from assimilated form of ex- "out" (see ex-) + vocare "to call" (see voice, n.).Evocatio was used of the Roman custom of petitioning the gods of an enemy city to abandon it and come to Rome; it also was used to translate the Platonic Greek anamnesis "a calling up of knowledge acquired in a previous state of existence."