The traits the word 'childish' addresses are seen so often in adults that we should abolish this age-discriminatory word when it comes to criticizing behavior associated with irresponsibility and irrational thinking.
If you don't begin to be a revolutionist at the age of twenty, then at fifty you will be a most impossible old fossil. If you area red revolutionary at the age of twenty, you have some chance of being up-to-date when you are forty!
I know not how to aid you, save in the assurance of one of mature age, and much severe experience, that you can not fail, if you resolutely determine, that you will not.
My heart is moved by all I cannot save: so much has been destroyed I have to cast my lot with those who age after age, perversely, with no extraordinary power, reconstitute the world.
"There's been a quantum leap technologically in our age, but unless there's another quantum leap in human relations, unless we learn to live in a new way towards one another, there will be a catastrophe."