Final answer:
Franklin was upset by a childhood event that made him cry with vexation. It is suggested that the event possibly involved a separation from his family or loved ones, leading to Franklin's emotional distress.
Step-by-step explanation:
Franklin was upset by an event in his childhood that made him cry with vexation. Although the specific event is not mentioned in the given reference, we can infer that it was significant as it had a lasting impact on Franklin. The text mentions that Franklin learned many new words that day, including words like mother, father, sister, and teacher, which made the world blossom for him. This suggests that the event possibly involved a separation from his family or loved ones, which could explain his emotional distress.