What, in your opinion, was the main reason for the defeat of Darius?

While the Persians pressed Alexander’s right flank, he himself, at the head of the heavily armed cavalry, entered; to the rear and fell on Darius, surrounded by bodyguards. He did not accept the battle and fled. All his army rushed after him.

One of the components of a person's success in our time is receiving modern high-quality education, mastering the knowledge, skills and abilities necessary for life in society. A person today needs to study almost all his life, mastering everything new and new, acquiring the necessary professional qualities.