Genesis 2:9 - Joseph Benson’s Commentary on the Old and New Testaments

Every tree pleasant to the sight That was calculated to render this garden the most beautiful place on earth; and good for food That is, agreeable to the taste and useful to the body. So that both man's mind and body were gratified and enriched. The tree of life also So called, it seems, not only because it was intended to be a sign to Adam, assuring him of the continuance of life and happiness, on condition of his persevering in obedience; but also because God had given to the fruit of it a singular virtue for the support of nature, the prolongation of life, and the prevention of all diseases, infirmities, and decays through age, as appears, Genesis 3:22. The tree of knowledge, &c. So called, not because its fruit had any virtue to beget useful knowledge, but because by it God would try Adam's obedience, and by eating of it man would know the good which he had lost, and the evil into which he had fallen by his disobedience.