"To see the truth" means to perceive or understand the reality or facts of a situation, rather than being misled by misconceptions or falsehoods. Full definition
People can not see the truth in the darkness, therefore things that once were right and functional have brought confusion to society. (globaleducationmagazine.com)
Often there's those logs in my eyes that keep me from seeing the truth of myself. (nakedpastor.com)
It has to do with that annoying log in your eye, you just can't see the truth about yourself. (religion.blogs.cnn.com)