when we see its exterior—not because its interior cannot be perceived by the senses, but because it is concealed, or for some other reason.

This, too, is one source of their error: in discussing perceptible things, they may fail to distinguish between what we actually perceive and what can be perceived, even though we are presently unable to perceive it.

If by “perceptible” he means the former, then undoubtedly some individual things are perceptible and others are not. The unseen matters of which the prophets have informed us are not perceptible to us: we do not witness them now; rather, they are hidden from us. Yet they can be perceived by the senses, and people will perceive them after death.

For this reason, the prophets, peace be upon them, spoke of things as either unseen or witnessed. Allah Most High said:

“Those who believe in the unseen” [al-Baqarah: 3].

And He said:

“That is from the news of the unseen which We reveal to you” [Hūd: 49].

And He said:

“He is Allah, other than whom there is no deity, Knower of the unseen and the witnessed. He is the Most Compassionate, the Most Merciful” [al-Hashr: 22].

These thinkers, however, divide things into the perceptible and the intelligible. The intelligible, properly speaking, is what exists in the mind. External existents, by contrast, can be apprehended by the senses, and perceiving them through the senses may depend on conditions that are now known with certainty.