When the subject disappears in the object, when the object disappears in the subject, when there is nothing to look at and there is no looker-on, when simply the duality is not there, that is SAMADHI. In other words, SAMADHI is made from the combination of 2 words – SAMA (Equanimity) and Buddhi (Intellect). Thus, when the intellect becomes equanimous i.e. when it looses the discriminatory dimension and just becomes perception; one experiences Samadhi.
Remember, this is the possibility for all of human beings. But the tricky part is when we experience the world we get smeared with the events so much that we forget about the ultimate human potential. In collecting pebbles and shells on the seashore one may miss the utterly blissful treasure of the ocean. This does not mean we do not enjoy the world!!! But the skill is not to get lost in it. Enjoy everything, but don't make it your very life then one will miss it. And remember, wherever we pay our attention that becomes the reality of life. If you pay your attention to pebbles, they become diamonds -- because wherever is your attention, there is your treasure. Sometimes the attention can be focused on the unreal and we start believing it to be real.
So make sure that real has to be sought. And the only way to reach it is, first, drop too many objects, let there be one object: second, drop all distractions. Let consciousness fall on that object in an uninterrupted. And the third (Samadhi) happens by itself. In that stillness, one can attain to the goal of life.