Our ignorance must necessarily be infinite

From Karl Popper in Conjectures and Refutations: The Growth of Scientific Knowledge.

The more we learn about the world, and the deeper our learning, the more conscious, specific, and articulate will be our knowledge of what we do not know, our knowledge of our ignorance. For this, indeed, is the main source of our ignorance - the fact that our knowledge can be only finite, while our ignorance must necessarily be infinite.