Though he was wrong on many or most things, Hegel did make a statement, that, in a rational mind, is true:
The true is the whole.
In other words, all knowledge is interrelated and interconnected. To acquaint oneself with math in one class, history in another, literature in another, grammar in another, and to never make connections between them or to life (or to make few, limited connections) is to not know the truth, is to not have real knowledge, is to not be logically connected to the world on principle.
An application, on a limited, small scale of Hegel’s idea might be like the oath some take in court: to tell “the truth, the whole truth, and nothing but the truth.”