If it is true that...

Essence is found in substances and in accidents

and

Essence is found in composite substances and in simple ones

and

The universal intentions of logic are found in substances, accidents, composite substances, and simple ones

Then it must be true that...

Being and essence are the things first conceived of by the intellect

If it is true that...

Being and essence are the things first conceived of by the intellect

Then it must be true that...

Knowledge of simple things should be acquired from composite ones