Swift has now concluded his illustration on humans' basic nature. Gulliver could not make himself a horse. He is not innocent or rational. He is, by nature, a Yahoo. But, as a European Yahoo, Gulliver should use his driblet of reason to improve himself; instead, he uses his reason to magnify his worst vice: his pride. Gulliver's pride has swelled out of all proportion; he has "reasoned" himself into rejecting his species and his nature: Gulliver is virtually a madman. His attitudes when he arrives in London make him a source of derision, for Gulliver seeks to change his basic nature by thinking; reason becomes the sole guide of his life.