In this task, you're given a story (which contains five sentences only). Your task is to find all the characters which are available in the given story.
Q: Sentence1: I've been reading my way through the works of Plato. Sentence2: My biggest question is whether Socrates actually existed. Sentence3: If not, Plato was very clever for inventing him. Sentence4: I've asked professors about this. Sentence5: They informed me that we can not be sure, but he probably existed.
A:
I (myself), Professors