Here is an adaptation of a Sufi teaching. (It can be viewed as an analogy):
There are four levels of knowledge.
They will be illustrated using a moth and a flame.

1. A moth hears a rumor or receives a teaching from a wiser and learned moth concerning the flame, which it assumes is God. The wise one speaks truly and imparts much knowledge which spans mystical revelation and several of the physical sciences. The moth who truly hears the wise man has acquired the first degree of initiation, the Lore lf Certainty. He has not acquired the Truth, and he may not even believe the wise teacher, nevertheless he has achieved the Lore of Certainty.

2. A moth has heard of the flame and has traveled to investigate it. He sees the flame for himself and he realizes that the wise moth spoke truly. He also realizes that the teachings of the wise could not possibly do the flame justice. And the aspiring moth may even make some critical judgments himself adding to the Lore of Certainty. This moth has achieved the second degree of initiation, The Eye of Certainty.

3. A more foolish moth is not content with the knowledge he has gained once he has achieved the Eye of Certainty. He decides to go closer, to experience it more directly. In doing so he comes to close and his wings are singed. He becomes wise indeed because he has achieved the higher level of knowledge. He has not just seen the truth, but he has felt it. He has achieved the Truth of Certainty.

4. Another moth decides that even the Truth of Certainty is not enough. It suspects that there is still a higher level of initiation, although all of the wisest assures him that there is not, and that he would be a fool to try. Ignoring all advice he joins the flame and merges with it, thus achieving the highest degree of initiation. His very essence has become one with the flame. This the Essence of Certainty.