PREFACE. X done something, if not towards directly effecting that object, at least towards opening the way for subsequent endeavours. If he has not sue- ceeded in putting all his propositions in a clear light, and finally settling the various contro- verted questions which he brings under review, yet he may hope that he has introduced them in such a manner as will excite in others the interest and attention requisite for their ultj- mate determination. Free, on his own part, from particular attachment to any of the po- sitions which he has maintained, although im- pressed with that clear conviction of their soundness, without which it would be absurd to intrude them on public notice; and sensible of the thousand ways in which error imposes itself on the understanding in the character of truth, he will be glad of an opportunity of re- considering his opinions, under the guidance of 2 mind which has reached a higher point of