Knowledge is power.
I know that author is taking shadow as a witness metaphorically.
I doubt if anybody has ever claimed to not have committed any crime in his whole life. If you see somebody claims, he is a big liar.
However, our conscience is always with us which shakes and jerks our inner soul and mind before committing any crime. If we do not hear the silent voice of our conscience, then it refrains from warning us further. And we no more feel shame or hesitation while doing misdeeds or sins. We don't mind to cheat our friends, relatives or even siblings.
I think we should listen to what our conscience speaks to us. It is the best judge and a guide for us which decides what is good for us and what is bad.
K Mohan @ Moga
'Idhuvum Kadandhu Pogum "
Even this challenging situation would ease