In the Qur’an, the law of fasting is explained in detail in verses 183 to 187 of Chapter Baqarah. Two important things are mentioned in these verses. One is that you fast and become pious, i.e. those who fear Allah and refrain from disobeying Him, and the other is that you become grateful.
Among them, the first thing i.e. piety is the purpose of fasting and the second thing i.e. gratitude is the essence of fasting. The difference between purpose and essence is that purpose is achieved after performing an action, whereas essence refers to the realization of a truth, a realization that can only be obtained by performing the action.
Allah achieves these two things in fasting by restricting fulfillment of basic needs like hunger and thirst. It is very hard to stop eating and drinking. But a believer does it on the command of Allah while fasting. If a person does this for thirty days with intentionally, he realizes that if he can refrain from eating and drinking on the command of God, giving up sin and disobedience is a much smaller challenge. This refraining from disobedience is the very piety declared as the purpose of Ramadan.
Deprivation of food and water during fasting makes a person realize how generously the fundamental blessings of life are available to him. He eats when he wants and drinks when he wants. So is the case with every other fundamental blessing. But man forgets these fundamental blessings and complains about the minor deprivations. He becomes despondent and ungrateful. But the hunger of a long fast and the thirst during heat remind him of all the fundamental blessings he has. Thus, if a person has consciousness, he becomes truly thankful by fasting.
Translated by Ali Zafar