Ver. 43. _Their generation's so equivocal._] It is sufficient that a principle of philosophy has been generally received, whether it be true or false, to justify a poet's use of it to set off his wit. But to recommend his argument, he should be cautious how he uses any but the true; for falsehood, when it is set too near the truth, will tarnish what it should brighten up. Besides, the analogy between natural and moral truth makes the principles of true philosophy the fittest for this use. Our poet has been pretty careful in observing this rule. Ver. 51. _And mark that point where sense and dulness meet._] Besides the peculiar sense explained in the comment, the words have still a more general meaning, and caution us against going on, when our ideas begin to grow obscure, as we are then most apt to do, though that obscurity be an admonition that we should leave off, for it arises, either from our small acquaintance with the subject, or the incomprehensibility of its nature, in which circumstances a genius will always write as badly as a dunce. An observation well worth the attention of all profound writers. Ver. 56. _Thus in the soul while memory prevails, The solid pow'r of understanding fails; Where beams of warm imagination play, The memory's soft figures melt away._] These observations are collected from an intimate knowledge of human nature. The cause of that languor and heaviness in the understanding, which is almost inseparable from a very strong and tenacious memory, seems to be a want of the proper exercise of that faculty, the understanding being in a great measure unactive, while the memory is cultivating. As to the other appearance, the decay of memory by the vigorous exercise of fancy, the poet himself seems to have intimated the cause of it in the epithet he has given to the imagination. For if, according to the atomic philosophy, the memory of things be preserved in a chain of ideas, produced by the animal spirits moving in continued trains, the force and rapidity of the imagination, breaking and dissipating the links of this chain by forming new associations, must necessarily weaken, and disorder the recollective faculties. Ver. 67. _Would all but stoop to what they understand._] The expression is delicate, and implies what is very true, that most men think it a degradation of their genius to employ it in what lies level to their comprehension, but had rather exercise their talents in the ambition of subduing what is placed above it. Ver. 80. _Some, to whom heaven, &c._] Here the poet (in a sense he was not, at first, aware of) has given an example of the truth of his observation, in the observation itself. The two lines stood originally thus: There are whom heav'n has blest with store of wit, Yet want as much again to manage it.