"The tree of knowledge, so-called, has become an instrument of death. Satan has artfully woven his dogmas, his false theories, into the instruction given. From the tree of knowledge he speaks the most pleasing flattery in regard to the higher education. Thousands partake of the fruit of this tree, but it means death to them. Christ says, “Ye spend money for that which is not bread.” Isaiah 55:2 . You are using your heaven-entrusted talents to secure an education which God pronounces foolishness. CT 12.2"
"Wherefore do ye spend money for that which is not bread? and your labour for that which satisfieth not? hearken diligently unto me, and eat ye that which is good, and let your soul delight itself in fatness."
Ellen White directly references Isaiah 55:2 in this passage.