It is said that still waters run deep. There is almost always more than what meets the eye. You can read a book, but unless you read between the lines, you might miss something. What meets the eye can be misleading, a trick, a deception. A seemingly deep pond of water can hold a dangerous rock just underneath that can kill or cripple. Do not take things at a glance. Learn to probe, learn to look for what is not there. Just because a man looks, it does not mean that he sees.