Evolution of love

What is the cause of the attachment ?

It arises because of the momentary reactions of liking and disliking. Liking develops into great craving; disliking into great aversion, the mirror image of craving, and both turn into attachment.
And why these momentary reactions of liking and disliking?
Anyone who observes himself will find that they occur because of bodily sensations.
Whenever a pleasant sensation arises, one likes it and wants to retain and multiply it.
Whenever an unpleasant sensation arises, one dislikes it and wants to get rid of it.
Then why these sensations?
Clearly they occur because of the contact between any of the senses and an object of that particular sense: contact of the eye with a vision, of the ear with a sound, of the nose with an odour, of the tongue with a taste, of the body with something tangible, of the mind with a thought or an imagination.

As soon as there is a contact, a sensation is bound to arise, pleasant, unpleasant, or neutral.
Every sensation, whether gross or subtle, has the same characteristic of impermanence.
A gross sensation arises, seems to stay for some time, but sooner or later passes away.
A subtle sensation arises and passes away with great rapidity, but still it has the same characteristic.
No sensation is eternal. Therefore one should not have preferences or prejudices towards any sensation. When a gross, unpleasant sensation arises, one observes it without becoming depressed.
When a subtle, pleasant sensation arises, one accepts it, even enjoys it, without becoming elated or attached to it. In every case one understands the impermanent nature of all sensations; then one can smile when they arise and when they pass away.
Equanimity must be practised at the level of bodily sensation in order to make a real change in one’s life. At every moment sensations are arising within the body. Usually the conscious mind is unaware of them, but the unconscious mind feels the sensations and reacts to them with craving or aversion.
If the mind is trained to become fully conscious of all that occurs within the physical structure and at the same time to maintain equanimity, then the old habit of blind reaction is broken. One learns how to remain equanimous in every situation, and can therefore live a balanced, happy life.