What does Aquinas say about falsity in the book, Introduction to Saint Thomas Aquinas?

Truth and falsehood are both described in relation to the intellect. Aquinas addresses this subject in Article Two: Whether there is Falsity in the Senses? and the Third Article Whether Falsity is in the Intellect? Aquinas observes that while "the Philosopher" claims that the human intellect can have perfect knowledge, he uses Aristotle to refute this. He cites an observation made in De Anima that in the mind's understanding of things there is truth and falsehood.