Paul told the Galatians that you reap what you sow. Spurgeon in the quote below, taken from the Old Guys website, says something very similar in regard to the books that we read. Basically we are what we read. That’s worth pondering.
“Certain insects assume the colour of the leaves they feed upon; and they are but emblems of a great law of our being: our minds take the hue of the subjects whereon they think. “As a man thinketh in his heart, so is he.” Readers of trash become trashy; lovers of skeptical books become skeptical; and students of the Bible, who are in real earnest, become biblical, and display the qualities of the Bible. If you read, mark, learn, and inwardly digest the word of God, the qualities of that word will be displayed in you. A man fed on Bibline is a man indeed. In the history of heroes, there are none who show so much moral muscle and spiritual sinew as those who make the word of God their necessary food.”