"If people are good only because they fear punishment , and hope for reward, then we are a sorry lot indeed" ~ Albert Einstein
Hexagram #21 BITING, ERADICATING ( Huo Lei Shi Ke), Fire over Thunder or Fire over Wood if we talk about the element.
From the visualisation its like an open mouth but with an obstruction, the Yang Lin on the top and bottom represent the lips, the Yin represents the teeth and the Yang at the 4th line represents the obstruction which make the mouth cannot be closed properly or we can say also that its like we want to express something but because something obstruct in between, we aren't able to speak clearly.
This situation maybe like when we are in the marriage ceremony , " Speak now or forever hold your peace" is in an admonition to immediately share information that may not be known by others -- if you speak your mind, you say your piece. Or else keep this information to yourself for eternity --if you are going to keep quiet, you hold your peace.
The principle of this hexagram is to be able to control oneself and do unemotional approach with a result that can be viewed as honest and fair by people. Yes, when the situation is tough where punishment is necessary, DO IT but the punishment should be appropriate, wise, fair and just. We must be clear in mind, wise in action so we can prevent further damage or impairment.
Simple analogy is like "when kids made mistake, we as parents wanted them not to repeat their same mistakes, not just simply say sorry -- as sorry means you knew you were wrong, changed the attitude and behaviour -- so we also will give them a punishment. Punishment that we gave should have educational purpose so the same mistake won't be repeated". Acknowledgement of a mistake should lead to insight and perception, then everything will be good again.
From the element and energy perspective: the Thunder is like striking in the clear hot daylight or the Fire is releasing the powerful sunlight like a lightning, both of these energy has "light" in it that can show us the way, light up our path and also "power" to change the surrounding. We cannot just accept and adopt unconditionally what's given to us but we also need to give punishment to correct of what is not appropriate and need to be corrected.
The Wood ( Zhen Trigram) induces the Fire ( Li Trigram), this is not an easy task because when you produce/generate something you will also lose something, your energy will be drained and the result also sometimes not in your favour. That is why you need to have a clear mind, calm emotion, good of knowledge and wisdom to make things become better.
