After finishing this, we took up Whately's Logic, then first republished from the Encyclopedia Metropolitana, and finally the Computatio sive Logica of Hobbes. From this time I formed the project of writing a book on Logic, though on a much humbler scale than the one I ultimately executed.
After this, I went in a similar manner through the Computatio sive Logica of Hobbes, a work of a much higher order of thought than the books of the school logicians, and which he estimated very highly; in my own opinion beyond its merits, great as these are.
“Errare non modo affirmando et negando, sed etiam sentiendo, et in tacitâ hominum cogitatione contingit.”—HOBBES, Computatio sive Logica, chap. v.