Quintilian, a Roman rhetorician during the Renaissance period, stated, "Our minds are like our stomaches; they are whetted by the change of their food, and variety supplies both with fresh appetite". Bertolt Brecht, in writing Life of Galileo, plants the essence of Quintilian's quote in his text through Galileo's actions. Though Galileo loses his passion for science, his appetite for food always remains, reflecting his acceptance of reality and abandonment of his ideal for human reason.
Near the beginning of the work, Galileo's appetite for food is significantly less important than that for knowledge, as he firmly holds on to his belief that humanity will readily accept the knowledge he provides. His appetite for food is overshadowed to a point where the readers can hardly notice his eating without the stage instructions. Yet Brecht repeatedly shows the readers the overlapping image of food and knowledge; he hands his apple down to Andrea after he used it as a prop to explain his findings, as if he is passing down knowledge. The apple is consumed neither by Galileo nor Andrea, but instead continuously handed down to those oblivious to the truth. Galileo's devotion to informing people is associated with his resolute trust in human reason: "Yes, I believe in reason's gentle tyranny over people. Sooner or later they have to give in to it" (27). He simply supposes that people have got to give into the "seduction of proof" (30), and certainly believes that passing down knowledge will immediately inflict a change on society.
Galileo's appetite for food surfaces as he realizes that knowledge passed down will not necessarily be always accepted. Galileo previously believed that "the only truth that gets through will be what we force through" (65). By using the word "we", he includes himself to the general public, demonstrating his confidence in receiving support from the people.