There are two flames that are in the Mishkan - the Ner Tamid and the Eish Tamid. The Ner Tamid was the flame that burned continuously on the Menorah, and the Eish Tamid was a fire that blazed without fail on the מזבח (seeויקרא ו:ו ).
The fire on the מזבח was a large fire (see Rashi to ז:ה). It teaches us a great lesson. Just as the fire on the מזבח must always be intense, so too, we must light an intense "fire of Torah" within ourselves. Our intense fire of devotion should burn constantly. However, there is also the Ner Tamid of the Menorah, a small flame. This teaches us the importance of modesty. The fire which burned before God, while it appeared intense on the outside מזבח, also had the modest light of the Menorah inside the sanctuary. The same is true for us. Although we must radiate with Torah on the outside, on the inside we must be modest, not arrogant and ostentatious. We also have to remember that just as the flames burned continuously, we must always act in accordance with Hashem's wishes, and remain consistent in our Yiddishkeit, and we must show both enthusiasm and modesty in our constant pursuit of Torah.