 The notion of ‘composition’ plays a prominent role in Peter’s semantics. Before embarking on the specifics of the word ‘is’, he first looks into the compositiones involved in the noun and the verb. When it comes to the composition involved in the use of ‘is’, the starting-point for his account is the question whether the expression ‘is’ in a proposition of the form ‘S is P’ implies the ‘being’ of the composition. Whether it does or not depends on how we consider the composition. If we are talking about any composition whatsoever, in his words, the composition in general, the composition can indiscriminately be connected with beings and non-beings. This is because we can talk about both things that are and things that are not by making use of the same affirmative propositions. Hence anything expressed by a proposition of the form ‘S is P’ is a being in a certain sense (ens quodammodo). The type of composition he is referring to here is the mental content of some affirmation, which is something that only has being to a certain degree. However, the composition in general, that is, the state of affairs involved in such expressions, is primarily connected with being rather than non-being. It is when we talk about non-beings, such as chimaeras, that being in a certain sense once again enters the scene. Hence a distinction of the types of being referred to, or the types of composition involved in affirmative propositions into being in the absolute sense (ens simpliciter) and being in a certain sense (ens quodammodo). The difference between these two types of being is illustrated by the distinction between two types of inference: from ‘A man is an animal’, in which the composition involved is a being in the absolute sense, it follows ‘Therefore a man is’, but from ‘A chimaera is a non-being’, in which the composition is a being in a certain sense only, it does not follow ‘Therefore a chimaera is’.