Svavisyāsamprayoge cittasvarūpanukara ivendriyānām prayāhārah | 2-54
Pratyahara is that by which the senses do not associate with their respective sense objects, they resemble the nature of the mind.
Pratyahara is withdrawer the power of senses from their respective object. It does not mean totally close yourself up from all the sense objects. We still have to do transection in our daily life which basically is contact with sense object alone. But our 5 organs of perception are comparable to the 5 horses of the chariot, they need to be control with the reins by the charioteer. In the same manner our 5 organs of perception consist of faculties of seeing, hearing, touching, smelling, and tasting, are need to be controlled by us through the mind. At initiate state one need to control over the external sense organ, drawing the boundary between the sense organs and their sense objects. Then slowly culminates into composure of the mind. When sense organs are as though well trained by the mind, then they are no longer go after to the respective sense objects.
The ultimate goal of meditation is staying in one own true nature, but when our mind is attracted / go after anything which is anātma (not my true nature), means we are giving a reality status to them. The senses seem to create this status of reality to the sense objects, and create differences between knower and the knowns. The fact, is that there is no difference between individual and universe. Just like in the dream, all the dreams objects are real in dream state itself, there is difference between the dream objects and the dreamer. But actually there is no devision between the dreamer and his dream. All the dream objecst is his knowledge alone. In this manner, how can we acknowledge that there is only one reality which is myself (my own true nature) and other things are exist depend on me, if we are giving the reality to them. Not to talk about staying in one own true nature which is Sat-cit-ananda. Because of not having the discriminative knowledge, one is living in the life of samsara / life becoming, always looking for happiness and freedom from external object. Happiness is not found inside, but happiness is oneself alone. After one wake up from the dream, he is no longer giving reality to the dreams.
Therefore pratyahara is not just withdrawal from the sense objects, but outgrown them with the understanding that they are only having the dependent reality.