  In the first section of his Commentary on Aristotle’s Physics Albertus Magnus discusses the possibility of the study of natural science. If science could only study particulars, Albert argues, then there would be no science in the sense of the demonstration of necessary causes because there would be as many sciences as there are particulars. But particulars, Albert goes on to point out, belong to definite kinds (species) and these can be studied because their causes can be demonstrated. Species have common attributes and a determined subject of which the attributes can be determined with necessity. Thus science is possible.