Matter and the account of what something is
Book II of the Physics illustrates material cause with bronze in a statue and silver in a bowl: that from which something is made and which remains in it. Material can be described at different levels according to the question.
Formal explanation concerns form or the account of what something is, not only its visible outline. Aristotle uses the octave’s ratio of two to one, showing how an organizing specification can explain the object.
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The origin of change and the end pursued
The originating or efficient cause is a primary source of change or rest, such as a maker in relation to what is made. Bronze and the sculptor’s art can both explain a statue without competing as answers to the same question.
Final explanation asks for the end pursued, illustrated by walking for health. Means and ends can form explanatory chains; exercise can produce health while health supplies the end for which exercise is undertaken.
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Several explanations in natural inquiry
Aristotle further distinguishes proper from incidental causes and actual operation from a capacity to act. Calling someone a sculptor explains production differently from naming an unrelated attribute that person happens to possess.
He also applies form, origins of change and ends to natural inquiry, sometimes bringing these explanations together. This belongs to his method of natural philosophy. Understanding the scheme requires separating the questions asked and assessing particular explanations, rather than endorsing every historical conclusion about nature.
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