In like manner as the passion for travel impels a man to perambulate the earth, and then makes him sigh to think that he has not other continents to explore, so the constitutional enthusiasm of speculation urges its victims to traverse the entire circuit of opinions: and even then leaves him insatiate of novelty. It is not caprice, much less is it the excessive solicitude of an honest mind, always inquiring for truth; but rather the impetus of a too highly-wrought intellectual activity, which carries the heretic onward and onward, from system to system, blazing as he goes, until there remains no form of flagrant error with which he has not scared the sober world. Then, though reason may have forgotten all consistency, pride has a better memory; and as this passion forbids his return to the truths he has so often denounced, and denounced from all points of his various course, nothing remains for him, when the season of exhaustion arrives, but to go off into the dark void of infidelity. The sad story has been often realized. In the conformation of the heretic by temperament, there is more of intellectual mobility than of strength: a ready perception of analogies gives him both facility and felicity in collecting proofs, or rather illustrations in support of whatever opinion he may adopt. So copious are the materials of conjectural argument which crowd upon him, and so nice is his tact of selection, and so quick his skill of arrangement, that ere dull sobriety has gathered up its weapons, he has reared a most imposing front of defence. Pleased, and even surprised, with his own work, he now confidently maintains a position which at first he scarcely thought to be seriously tenable. Having convinced himself of the certainty of the new truth, and implicated his vanity in its support, deeper motives stimulate the activity of the reasoning and inventive faculties; and he presently piles demonstration upon demonstration, to a most amazing height, until it becomes, in his honest opinion, sheer infatuation to doubt. In this state of mind, of what value are the opinions of teachers and of elders? Of what weight the belief of the catholic church in all ages? They are nothing to be accounted of; there seems even a glory and a heroism, as well as a duty, in spurning the fallible authority of man: modesty, caution, hesitation, are treasons against conscience and heaven!