The idea of the flame is a metaphor for spirit (as in “broke his spirits” if that makes sense). Each human has a flame, and that flame is fueled by Zeal, goodness and spiritual achievement. It is put out by authority, apathy and lies. Tending to the flame is healthy, and improves spiritual development via subconscious stuff that i cannot really describe.

So to get into this idea of tending the flame, we have to first look at Zeal. I have written a whole article on it, but simply, it is motivation and a pinch of anger triggered by the realization of higher truths and the defense of honorable ideals, essentially. It is something that should be welcomed, and it certainly can help your flame burn brighter.

Another thing about the flame; it can dim while you are not looking! For example, you are at a party with your peers/family, drinking and not really thinking about your situation in a proper way. The day after, let’s say you do a protection working yet something feels off, it is more draining than usual. Why? You let your mind slip into a place where it should not be. You allowed your flame, your spirits, to be dimmed because you fell into an easy headspace. You need not have to think there. You must only relax, and lose all self-awareness! Why we do this as a society is beyond me, but remind yourself that being self-aware and thought are things that should be happening all the time.
Now, let me add this, it would be extremely easy for me to sit here and tell you that the flame is simply a way of thinking about motivation, but it is quite a bit more complicated than that. It’s a mix of zeal, positive feeling, honorable action, motivation and energy (as in tired/awake). When a practical approach to psychology is attained, and i will elaborate further later on in the book, deeper understanding of the way your brain works can be used not only to further your practice via subconscious jiggery-pokery, you can stoke the fire and grow the flame.
In this journey, you must know this; the road of truth and spirituality is not an easy one to take! The understanding that people near you, loved ones and treasured friends, and you for that matter have been brainwashed in an awful capitalistic loop is not a very good one. And here it would be very easy for me to say “Abandon them and live in truth! Give me all your money and i’ll tell you how!”, but in reality the path to truth and goodness is a long and complicated winding road. Now, if you were listening, at every political discussion you have with people you know, you will pose interesting questions that make people think, you will cause people to sit and think about questions and come to the logical conclusions that we have. Maybe they will join the society, or even take this course! 
We need to get people thinking. We need to get people understanding. We need to get people breaking out of their chains and showing the reactionaries the truth. We need to get better. Or we all die because either the planet is too hot or the new GoodCitizen policing bots decided we were thinking too much.
The idea of occasional seriousness is a serious problem. Why do people only think about religion on sundays? Why do people only think about politics when they go to vote? And why, please tell me, do people only think on occasion?