We would be deceiving ourselves profoundly if we thought that fasting, which has been practiced in many different forms and degrees in Christian tradition - total fasting, fasting from meat, a diet of vegetables or of bread and water - could be replaced by any other form of ascetic discipline. Eating is particularly significant because it is an infant's first way of relating to the external world. Infants are nourished by their mother's milk, but as they are initially unable to distinguish their mother from food, they also seek nourishment in all that surrounds them. They 'eat' and take in voices, odors, shapes, and faces, and through this process they gradually construct a personality, relationships and an emotional life. This means that the symbolic value of fasting is connected to all of the external aspects that contribute to the construction of our identity. Other forms of asceticism cannot be considered 'equivalents' to fasting, because they are associated with other symbolic values and are thus unable to carry out fasting’s unique function. Different ascetic practices are not interchangeable! When we fast, we learn to recognize and control our many appetites by first controlling our most basic and vital appetite, hunger. We learn to exercise discipline in our relationships with others, with external reality and with God, relationships in which the temptation of voracity is always present. Fasting is a way of disciplining our need and educating our desire.