What scepticism doubts is that reason (principle of certitude) can reach any conclusion working on the data of the senses.

Do properties constitute substance?

Properties of the mind: intensity of sensations.

As the body so the soul. As the brain, the mind, as the mind, the brain. As the muscles the strenght. Strenght is not matrial. The brain represents the mind as the muscles the strength.

Reading developing brain power.

Materialist: Force acts on matter. This is not conceivable, unless it be held that matter and force are of the same nature. The unlike cannot act on the unlike.

Cause and origin.

Cause: like on like.

Origin: the unlike produces the unlike.