triangle has no obtuse or right angle:  all these truths admit of no exception.  There never can be any being, line, circle, or triangle, but according to these rules.  These axioms are of all times, or to speak more properly, they exist before all time, and will ever remain after any comprehensible duration.  Let the universe be turned topsy-turvy, destroyed, and annihilated; and even let there be no mind to reason about beings, lines, circles, and triangles:  yet it will ever be equally true in itself, that the same thing cannot at once be and not be; that a perfect circle can have no part of a straight line; that the centre of a perfect circle cannot be nearer one side of the circumference than the other.  Men may, indeed, not think actually on these truths:  and it might even happen that there should be neither universe nor any mind capable to reflect on these truths:  but nevertheless they are still constant and certain in themselves although no mind should be acquainted with them; just as the rays of the sun would not cease being real, although all men should be blind, and no body have eyes to be sensible of their light.  By affirming that two and two make four, says St. Augustin, man is not only certain that he speaks truth, but he cannot doubt that such a proposition was ever equally true, and must be so eternally.  These ideas we carry within ourselves have no bounds, and cannot admit of any.  It cannot be said that what I have affirmed about the centre of perfect circles is true only in relation to a certain number of circles; for that proposition is true, through evident necessity, with respect to all circles ad infinitum.  These unbounded ideas can never be changed, altered, impaired, or defaced in us; for they make up the very essence of our reason.  Whatever effort a man may make in his own mind, yet it is impossible for him ever to entertain a serious doubt about the truths which those ideas clearly represent to us.  For instance, I never can seriously call in question, whether the whole is bigger than one of its parts; or whether the centre of a perfect circle is equally distant from all the points of the circumference.  The idea of the infinite is in me like that of numbers, lines, circles, a whole, and a part.  The changing our ideas would be, in effect, the annihilating reason itself.  Let us judge and make an estimate of our greatness by the immutable infinite stamp within us, and which can never be defaced from our minds.  But lest such a real greatness should dazzle and betray us, by flattering our vanity, let us hasten to cast our eyes on our weakness.

Sect.  LIII.  Weakness of Man’s Mind.