Taste Of Light
The Baal Shem Tov gave the following example:
A person comes into a store where they sell many types of delicacies and sweetmeats. The first thing that the storekeeper does is give him a sample of each kind, in order that the customer should have an idea what to buy. When he tastes it and sees how good it is, he wants to sample more. But the storekeeper says, "You have to pay for what you take. We do not give away anything for free."
The "free sample" is the Light that a person experiences when he begins to draw close to Hashem. Through this taste of light, he should subjugate all evil and bring it back to the good. This is the "free sample" that he is given, so that he will realize the taste of true davening. A taste of this remains after the light is withdrawn, so that he will know what to seek.
(Rebbe Yitzchok Isaac of Komarno)