North Whitehead, Alfred – There is no such thing as matter, there are only energy, entities and relationships, and processes
Type of Spiritual Experience
Whitehead was convinced that the scientific notion of matter was misleading as a way of describing the ultimate nature of things.
In Whitehead's view, there are a number of problems with the notion of "irreducible brute matter."
First, it obscures and minimizes the importance of change. By thinking of any material thing (like a rock, or a person) as being fundamentally the same thing throughout time, with any changes to it being secondary to its "nature", scientific materialism hides the fact that nothing ever stays the same. For Whitehead, change is fundamental and inescapable; he emphasizes that "all things flow." What is ordinarily conceived of as a single person, for instance, is philosophically described as [and actually] a continuum of overlapping events.
Second, it obscures the importance of relations. It sees every object as distinct and discrete from all other objects. Each object is simply an inert clump of matter that is only externally related to other things. The idea of matter as primary makes people think of objects as being fundamentally separate in time and space, and not necessarily related to anything. But in Whitehead's view, relations take a primary role.
A description of the experience
Alfred North Whitehead - Science and the Modern World,
There persists ... [a] fixed scientific cosmology which presupposes the ultimate fact of an irreducible brute matter, or material, spread through space in a flux of configurations. In itself such a material is senseless, valueless, purposeless. It just does what it does do, following a fixed routine imposed by external relations which do not spring from the nature of its being. It is this assumption that I call 'scientific materialism.' Also it is an assumption which I shall challenge as being entirely unsuited to the scientific situation at which we have now arrived.