The psalmist wrote:
מַה גָּדְלוּ מַעֲשֶׂיךָ ה'; מְאֹד עָמְקוּ מַחְשְׁבֹתֶיךָ
"How great are Your acts, God; how deep are Your thoughts." (Psalms 92:6)
What is the difference between the "greatness" of God's acts and the "depth" of His thoughts?
Three Types of People
Imagine a giant sequoia, towering hundreds of feet into the sky. People passing by the magnificent redwood will fall into three categories:
Some people will pass right by the sequoia, without even noticing its extraordinary height.
Others will lift their eyes and be astonished by its enormous size.
The psalmist noted that he was amazed by both aspects of God's works. He was aware of that which is revealed to the eye - "How great are Your acts." And he has the insight to realize that there is just as much that is hidden from our sight - "how deep are Your thoughts."
But there are obtuse individuals who go through life without ever noticing the wonders of the universe. As the psalm continues, אִישׁ-בַּעַר לֹא יֵדָע - "But a boorish person does not know." The boor lives his life without even noticing the magnificent sequoia.
And there are others - perhaps most people - who only discern that which is revealed to the eye. וּכְסִיל לֹא יָבִין אֶת-זֹאת - "The fool fails to understand this." The fool is duly impressed by the redwood's amazing height. But he fails to realize that there must be a whole side of the immense tree which is hidden from sight, deep under the ground. For all that we are amazed by the wonders of the world, there is just as much hidden from our sight and understanding.
(Adapted from Mishlei Yaakov, pp. 380-381)