As per Ayurveda, the modes of nature have been divided into three categories, Sattva, Rajas and Tama. They are the modes which act mainly on the physical and the mental behavior of a person and hence, have a nice as well as a predominant effect on the nature of a person.
The third and the most condemned guna is Tamo Guna or the mode of ignorance. This is the mode of carelessness and is directly with a negative and opposite mind. When one comes in the mode of ignorance, he can experience that his senses have gone to the verge of ignorance and are doing what is not to be done and are not doing which is to be done. Whatever wrong they do, they get firm conviction in the same that I am right.
The scripture Bhagwad Gita illustrates the effect of mode of passion on various activities.
Bg 14.8 — O son of Bharata, know that the mode of darkness, born of ignorance, is the delusion of all embodied living entities. The results of this mode are madness, indolence and sleep, which bind the conditioned soul.
Bg 14.9 — ignorance, covering one’s knowledge, binds one to madness.;.
Bg 14.13 — When there is an increase in the mode of ignorance, O son of Kuru, darkness, inertia, madness and illusion are manifested..
Bg 14.15 — When one dies in the mode of ignorance, he takes birth in the animal kingdom.
Bg 14.16 — and action performed in the mode of ignorance results in foolishness.
Bg 14.17 — from the mode of ignorance develop foolishness, madness and illusion.
Bg 14.18 — and those in the abominable mode of ignorance go down to the hellish worlds.;
This is a brief description of a personality situated in the mode of passion. Mode of ignorance is predominated by the astringent taste i.e. tastelessness and the food which is obnoxious. Food prepared more than three hours before being eaten, food that is tasteless, decomposed and putrid, and food consisting of remnants and untouchable things is dear to those in the mode of darkness.. (Bhagwad Gita 17.10).
When a person is in the mode of ignorance, he is firm that what is good for him is actually bad and what is bad for him is actually good. He is very much lethargic, sleepy, mad and has got no control over his mind. Such a person becomes definitely commits Pragyaparadh, the cause of all mental miseries in the science of Ayurveda. He eats what is forbidden due to the urge of his tongue and what is not good for his health. He knows what the seasonal regime is and what is to be taken and what is not to be taken, but never cares to follow it. Since his senses are illuminated by ignorance, he has a faulty mindset and hence, is prone to mental illness.
He comes to the stage of madness and insanity and hence, has to suffer the result of the same.