“Over and above this, my son, be warned. Of the making of many books there is no end and of much study there is exhaustion of the flesh.”
For the record, Solomon is not saying that study is unfruitful, though that is sometimes how this passage is interpreted. He states that it will exhaust you physically (don’t miss the “to the flesh”). For indeed, as we have already seen in Solomon’s writings, there is profit in learning and in growing in one’s understanding so long as that learning remains in the context of the Word of God. Such is the significance of the first phrase found within this passage — do not go beyond “these things.” What are the things to which Solomon points? He is pointing toward the collected sayings and the words of the wise.
And so, there is a principle set before us — set the word of God before you, study it and dig into its depth even if it is wearisome to the flesh. The infinite depth of the word is a testimony to the fact that Scripture is of God; were it not, we would have long ceased to have anything to say about it. Yet, as it is, every generation will add to the corpus of knowledge and understanding of the inspired Word. Study these two, just do not go beyond the Canon of the Bible.
Can you study secular books then? Yes. At the same time, use the Scriptures as a lens by which you view these secular books. Use the Scriptures as a rule and guide to evaluate such things. So, be warned, though you may find yourself weary in your flesh, your mind and spirit will grow to maturity on the basis of such things…just be warned not to go outside of the collected sayings and words of the wise contained in God’s Holy Scripture.