PROFESSOR McGONAGALL (to ALBUS and SCORPIUS)
Your intentions to save Cedric were honourable if misguided. And it does sound as if you were brave, Scorpius, and you, Albus, but the lesson even your father sometimes failed to heed is that bravery doesn’t forgive stupidity. Always think. Think what’s possible. A world controlled by Voldemort is—

SCORPIUS
A horrific world.

PROFESSOR McGONAGALL
You are so young. (She looks at HARRY, DRACO, GINNY and HERMIONE.) You’re all so young. You have no idea how dark the wizarding wars got. You were – reckless – with the world some people – some very dear friends of mine and yours – sacrificed a huge amount to create and sustain.

ALBUS
Yes, Professor.

SCORPIUS
Yes, Professor.

Harry Potter and the Cursed Child - Chapter 3 :
See this quote in the Pensive -