Aeschylus (fifth century B.C.) - This quote is a fantastic example of a chiasmus - at its core, Aeschylus is saying that a promise is only as reliable as the person making it. If a known liar or a scam artist swears a solemn oath, you still aren't going to trust them. The ceremonial words of an oath do not magically make a person honest. Instead, it is the established integrity and character of the individual (the "man") that gives the oath its credibility. A person's character validates their promise, not the other way around.
This specific quote is cataloged as Fragment 385 of Aeschylus's surviving texts. Because it is a "fragment," it survived from one of his many plays that were unfortunately lost to history over the centuries. While we don't know the exact plot or the characters who spoke this line, it perfectly reflects the ancient Greek philosophical focus on ethos (character) as the ultimate measure of a person's worth.
In fact Aeschylus (c. 525 – 456 BC) is widely recognized today as the "Father of tragedy". Before he came along, Greek theater essentially consisted of a single actor interacting with a chorus. Aeschylus changed the game by introducing a second actor to the stage. This single innovation allowed for face-to-face dialogue and dramatic conflict, effectively inventing theatrical drama as we understand it today.
He was a brilliant wordsmith whose influence is still felt. In fact, he is credited with being the first to express the famous sentiment, "Live by the sword, die by the sword." While most people associate that exact phrase with the Gospel of Matthew, Aeschylus wrote something remarkably similar centuries earlier in his masterpiece "Agamemnon" (line 1558):
By the sword you did your work, and by the sword you die.
Despite his profound wisdom and literary genius, Aeschylus is perhaps equally famous for the incredibly bizarre legend surrounding his death.
According to ancient historians like Pliny the Elder, Aeschylus visited an oracle and received a prophecy that he would be killed by a falling object. Understandably spooked, the playwright decided the safest bet was to spend all of his time outdoors in open spaces, away from buildings where a roof might collapse on him.
In 456 BC, while Aeschylus was sitting outside in Sicily, a hungry eagle flew overhead carrying a tortoise it had just caught. To get to the meat, eagles will drop tortoises from high altitudes onto hard rocks to shatter their shells. As the story goes, the eagle looked down, saw Aeschylus's smooth, shiny, bald head, mistook it for a rock, and dropped the turtle. The shell didn't break, but Aeschylus's skull did, killing him instantly and fulfilling the prophecy in the most absurd way possible.
It should be heavily noted that the ancient Greeks and Romans absolutely loved making up ridiculous, heavily ironic stories about how famous people died. Modern historians are almost certain this story is an apocryphal myth - perhaps even a joke started by rival playwrights - but it undeniably remains one of history's most unforgettable legends.