Their posterity approve their sayinys - Go the same way; adopt their maxims.
This their way is their folly - This might be rendered, “This is their way or course of life. It is their folly;” or, such is their folly. On the word “way,” see the notes at Psalm 1:6. The idea is, that it is folly for a man to cherish these hopes; to feel that wealth is of so much importance; to imagine that it can deliver from the grave; to suppose that he can perpetuate his own name, and secure his possessions in his own family upon the earth. And yet the world is still full of people as foolish as were those in the time of the psalmist; people who will not be admonished by the suggestions of reason, or by the experience of 6,000 years in the past. This is one thing in which the world makes no progress - in which it learns nothing from the experience of the past; and as the beaver under the influence of instinct builds his house and his home now in the same way that the first beaver did his, and as the brutes all act in the same manner from generation to generation, accumulating no knowledge, and making no advances from the experience of the past, so it is with people in their desire to grow rich. On other points the world accumulates knowledge, and profits from experience, garnering up the lessons taught by past experiment and observation, and thus becoming wiser in all other respects; but in regard to the desire of wealth, it makes no progress, gains no knowledge, derives no advantage, from the generations of fools that have lived and died in past ages. They now engage in the pursuit of gold with the same zeal, and the same expectation and hope which were evinced in the first ages of the world, and “as if” their own superior skill and wisdom could set at nought all the lessons taught by the past.
Yet their posterity - The coming generation is as confident and as foolish as the one that went before.
Approve their sayings - Margin, “delight in their mouth.” That is, they delight or take pleasure in what proceeds from their mouth; in what they say; in their views of things. They adopt “their” principles, and act on “their” maxims; and, attaching the same importance to wealth which “they” did, seek as “they” sought to perpetuate their names upon the earth.