Geeta is the philosophy that is purest form of introspection, their is nothing that can even come close to it, among all the literature I read during time of my depression, I could only understand Geeta.
There is an interesting point in Geeta when Arjun ask Shri Krishna that it would be better to leave everything and take sanyas & beg for food, as Arjun thinks that to fight a war against his own Kin ( i.e. Killing his Kin) will only give him sin, also, land, wealth etc are all materialistic thing, they don’t last forever.
Shri Krishna then guides him, he asks him that even if you take sanyas would you really be not doing anything? won’t you be searching for food? Is getting food so easy? don’t other living beings fight for their food? He tells Arjun that “you are not having control over your mind, you shouldn’t act like a coward, all your brothers & soldiers are ready to die in this war as they have been snatched away from their rights and at this time you are offering to quit, also if you are not happy when you are having everything then how could you be happy when you would not be having anything”.
He tells Arjun that if you quit in between this war then people will laugh at you, people will make anecdotal jokes on you, which will be circulated all across the places, if you think about yourself to be knowledgeable and sensible, then keep it in your senses that for a self respecting man there’s nothing worse then being called a coward.
He further guides him that if you are not happy with what you have been doing since a long time, and in fact you are not able to do something in which you are supposed to be second to none then how could you be happy in something which you have never done before? also, is living without your loved one is so easy?
Shri Krishna tells him that a true Sanyas is to not to worry too much about the consequences of an action, this doesn’t means that you should stop thinking, but you should not be possessive about anything, you can perform to best of your abilities, but what will be the outcome of your action is not in your hand.
Shri Krishna tells Arjun to look at Shri Krishna himself and learn that how he i.e. Shri Krishna himself is living his life, Shri Krishna was an ordinary shepherd, he didn’t get his lady love Radha, but he didn’t loose his heart or mind, his own uncle tried to kill him but he withstood them and in fact killed his uncle, he became a King himself, he ask Shri Arjun to learn from his life and make him his idol so that it is easy to guide his life by looking at the life of Shri krishna.