Below is an excerpt from, "The Soul of Kierkegaard: Selections from His Journals." Edited by Alexander Dru. Dover Publications, Inc: Mineola, New York. 2003. Pg. 191-192.
The difference between "popular" and "philosophical" is the amount of time a thing takes. Ask a man: do you know this, or do you not know it---if he answers immediately then the answer is popular, he is an undergraduate. If it takes ten years for the answer to come, and if it comes in the form of a system, if it is not quite clear whether he knows it or not: then it is a philosophical answer and the man a professor of philosophy---at least that is what he ought to be.