We know that the same condition of things pertained in Egypt, when science became static there.

But, contrariwise, we have seen that in Greece and early Rome the scientific workers were largely physicians or professional teachers; there was scarcely a professional theologian among them.
Similarly, as we shall see in the Arabic world, where alone there was progress in the mediaeval epoch, the learned men were, for the most part, physicians.

Now the meaning of this must be self-evident.

The physician naturally "intends" his mind towards the practicalities.

His professional studies tend to make him an investigator of the operations of nature.