Being asked how the educated differ from the uneducated, “As much,” he said, “as the living from the dead.”

[ἐρωτηθεὶς τίνι διαφέρουσιν οἱ πεπαιδευμένοι τῶν ἀπαιδεύτων, “ὅσῳ,” εἶπεν, “οἱ ζῶντες τῶν τεθνεώτων.”]

Aristotle (384-322 BC) Greek philosopher

Attributed in Diogenes Laërtius, Lives and Opinions of Eminent Philosophers [Vitae Philosophorum], Book 5, sec. 11 [tr. Hicks (1925), sec. 19]
    (Source)

(Source (Greek)). Alternate translations:

On one occasion he was asked how much educated men were superior to those uneducated; “As much,” said he, “as the living are to the dead.”
[tr. Yonge (1853)]

When asked what the difference was between those who were educated and those who were not, Aristotle said "as great as between the living and the dead."
[tr. @sentantiq (2016)]

When asked how the educated differ from the uneducated, he said, "as much as the living from the dead."
[tr. Mensch (2018)]