 Avicenna explains the inferiority of the lowest type of efficient cause as follows: This type gives being to an effect that does not exist after absolute nonexistence but after a specific privation in matter. Of this type of agent, he says that its power to give being to another is weak, of short duration, and intermittent (Avicenna MH: 204). Sublunary substances such as plants and animals are efficient causes of this lowest type.