1 Samuel 16:1-13
Psalm 89:20-22, 27-28
“God does not see as a human sees.” How does a human see? Well light comes from the light source such as a lamp or the sun and it bounces off an object. The nature of the object changes what kind of light and how much light bounces off. Then the light enters the human eye, causing chemical changes on the retina. This is how a human sees, but not God.
God knows everything perfectly. He does not see a thing as much as he simply knows all about it. No atom in the universe loses an electron without God being aware. So the first difference between the human sight and divine sight is that human sight is limited to those objects which we see light bouncing off of whereas God's sight is unlimited.
But there are other differences too. Even when we are looking at something and can see it perfectly, our brains cannot always process the information. This is what causes optical illusions. An optical illusion can be looked at with the best light and still fool us. One line seems longer than another but when we bring out the ruler we find that it is not. God's sight is different in this way too because he always understands perfectly everything he knows.
And even when we are able to see something and understand what it is we see, we might fail to catch the significance. If you see a ring on the fourth finger of a person's left hand you know that they are married, but if we went to a different culture we would probably miss their equivalent symbols. A small mark or a piece of jewelry or a color of clothing might signify something very important to those who understand.
God, of course, understands all these things. God can see into the human heart. We have trouble seeing into our own hearts, let alone the heart of another, but God can see clearly our thoughts and motivations, our fears and our dreams. The truth in my heart might be hidden so that not even I know it, but God does. So when God tells me what will make me happy, what I should do and what I should avoid, I can be sure that he knows me better than I do.