And as when you mix other birds' wings with the eagles', the plumes waste and suddenly consume; so there is no reason to the contrary, but that one man's touch may be good and advantageous, and another's hurtful and destructive.

But that some, by being barely looked upon, are extremely prejudiced is certain; though the stories are disbelieved, because the reason is hard to be given.
True, said I, but methinks there is some small track to the cause of this effect, if you come to the effluvia of bodies.

For smell, voice, breath, and the like, are effluvia from animal bodies, and material parts that move the senses, which are wrought upon by their impulse.

Now it is very likely that such effluvia must continually part from animals, by reason of their heat and motion; for by that the spirits are agitated, and the body, being struck by those, must continually send forth effluvia.

And it is probable that these pass chiefly through the eye.