Spurious faith, in which falsities are mixed with truths, can be compared with the defect of the eye and sight called white spot on the cornea, which makes the sight dim. Meretricious faith, which arises from falsified truths, and adulterous faith, which arises from different kinds of adulterated good, can be compared with the defect of the eye and sight called glaucoma, which is a drying-up and hardening of the crystalline humour.

[2] Concealed or blind faith, which is faith in mysteries which are believed in, despite ignorance whether they are true or not, or whether they are above the level of reason or contrary to it, can be compared with the defect of the eye called gutta serena or amaurosis, which is a loss of sight arising from the obstruction of the optic nerve, although the eye appears to be intact and seeing. Erratic faith, which is in a plurality of gods, can be compared with the defect of the eye called cataract, which is loss of sight due to blockage between the sclerotic tunic and the uvea. One-eyed faith, which is in some god other than the true one, and in the case of Christians in a god other than the Lord God the Saviour, can be compared with the defect of the eye called squinting. Hypocritical or Pharisaical faith, which is a faith of the lips, but not the heart, can be compared with atrophy of the eye leading to loss of sight. Imaginary or upside-down faith, which is falsity made by clever proofs to seem like truth, can be compared with the defect of the eye called nyctalopia, which is the ability to see by deceptive light in darkness.