We are always desiring for some object or the other thinking the object will give us happiness. There is always a nagging though I want, I want playing on our mind. The object of what I want, keeps changing.
Gita says that when we dwell on a certain object either after hearing about it or seeing it we desire to have that object. At that moment the thought I want gets joined with the thought of the object and we feel I want that object.
This thought disturbs our peace of mind. No one likes a disturbed mind. Therefore we strive to obtain that object. As soon as we get the object of desire the nagging thought I want subsides for some time. There is temporary pleasure. Therefore we conclude that the object has brought us happiness. But very soon again the nagging thought I want I want continues and disturbs my mental poise. This is due to an inherent feeling of lacking in us. The mind then keeps searching for another object to pacify this nagging. With all the advertising around us there is no dearth of objects for the mind to latch on to. Then we desire the next available object according to the fancy of our mind.
If the happiness is in the object, then when I got the first object of my desire my happiness should have been permanent. But it is never so. What I want and obtain today becomes an object of dislike tomorrow and I am eager to dispose it off. Moreover there is someone who is wanting to possess what I dislike and dispose off. So our ancient Rishis came to the conclusion that happiness is not centered on the object.
After deliberating on the nature of mankind and after a lot of meditation they came to the conclusion that Happiness is stored in me and happiness is my true nature.
The view of the ancient Rishis is that when we get an object of desire the mind becomes relatively calm and my true self which is of the nature of happiness springs forth and permeates to my mind also. Therefore it is my inherent happiness which is percolated on to my mind because at that moment my mind and myself are one with each other. So my mind borrows my happiness and we wrongly attribute the source of happiness to the object and conclude that the object has brought us happiness.
Ancient rishis have said that our true nature is Sat Chit Anandam which roughly translates as Existence Consciousness Bliss.
They therefore advise us to look within for the Kingdom of Heaven and say Atmanam Vidhi or Know thyself.