If, . . . my father had taken the pains to explain to me that the principles of Agrippa had been entirely exploded and that . . . the powers of [Agrippa] were chimerical, . . . I should certainly have thrown Agrippa aside. . .

A chimera is a deception or fantasy of the mind.

What is the effect of using the word chimerical to describe the powers of the principles of Agrippa?

It suggests Agrippa is no more than imaginary.
It suggests this period of time was crucial to the narrator.
It suggests the principles have the illusion of truth.
It suggests the speaker is haunted by his past.

I think the answer is the third one