  The mechanical philosophy differed from the atomism of the Greeks insofar as it was intended to apply to the material world only and not to the spiritual world. Apart from that major difference, the world-views are alike. Fundamentally there is just one kind of matter characterised by a property that serves to capture the tangibility of matter and distinguish it from void. Boyle chose absolute impenetrability as that property. There are insensibly small portions of matter that, whilst they are divisible in thought or by God, are indivisible as far as natural processes are concerned. Boyle, misleadingly drawing on another tradition that will be discussed in a later section, referred to these particles as minima naturalia or prima naturalia. Here they are referred to as atoms, a terminology only very rarely adopted by Boyle himself. Each atom has an unchanging shape and size and a changeable degree of motion or rest.  All properties of the material world are reducible to and arise as a consequence of the arrangements and motions of the underlying atoms. In particular, properties possessed by macroscopic objects, both those detectable directly by the senses, such as colour and taste, and those involved in the interaction of bodies with each other, such as elasticity and degree of heat, are to be explained in terms of the properties of atoms. Those properties of atoms, their shape, size and motion, together with the impenetrability possessed by them all, are the primary ones in terms of which the properties of the complex bodies that they compose, the secondary ones, are to be explained. Such explanations involve the fundamental laws of nature that govern the motions of atoms.