1.1. Lack as a cause of being A fundamental theoretical reflection on the essence of lack starts with Greek philosopher Aristotle (384–322 BC). To explain reality, Aristotle identifies three primary causes of being: form, matter and lack (στέρεσις, usually translated as privation). Origins have in common that they are the first of which something either comes into being or is known (Barnes 1984). Those causes are necessary for the process of defining being itself and enabling coming into being. For things to come into being, to exist and to change, it takes a) that which evolves; b) that which is in opposition to what evolves; and c) that out of which something evolves. According to Aristotle’s definition, a thing that evolves is the form, in opposition to it is lack, and those opposites operate in matter. To explain lack as an origin, a conceptual distinction has to be made between lack and nothingness. Lack is not absolute nothingness, but an actual non-being in a particular matter, which can Origins have in common that be actualized according to the they are the first of which form. For example, fire does not something either comes into come into being out of the abbeing or is known. sence of just anything, but only out of those things that have the potential to cause fire, like dry straw. Therefore, lack is to be understood in relation to matter – lack is not tantamount to pure nothingness or nothing. Lack is a cause because it makes becoming, change and advancement of all entities possible. Aristotle’s thoughts about the causes of being are developed further by medieval thinker Thomas Aquinas (1225–1274). In his early work, On the Principles of Nature, he interprets three characteristic and basic features of every entity. The new idea he points out is that matter and lack (privatio in Latin) concur according to the object, but differ in 20