"The more you know, the more you realize you know nothing."
There is an interesting explanation -- I have seen it attributed to the great mathematician Leonhard Euler -- of why we feel we know less when we have increased our knowledge.
Imagine a rectangle. The area contained in the rectangle can be thought of as the universe of everything that is to be known. Now imagine a small blob - a small coloured in area - in that rectangle. That blob represents the knowledge of someone who knows very little. A distance away imagine a larger blob with a somewhat irregular outline. That large blob represents the knowledge of a person who knows more, and who has attempted to increase his knowledge in selected areas.
If one traces the perimeters of the two blobs in the reactangle then one has a measure of each of these two person's contact with ignorance. The small blob would have to have a very irregular perimeter to be anywhere near as large as the perimeter of the larger blob. Normally, however, it is people with many interests who have larger areas of knowledge, and this will cause an irregular perimeter. So almost certainly the person with the larger blob will have a larger perimeter - and that means that person will have greater contact with ignorance.
Greater contact with ignorance means a a greater realization of how little one actually knows.