This is the other persons answer but i just helped with spelling answer:
The meaning behind the statement is that What is done cannot be undone. but that one can prevent it from happening again.
At a time when the Nazis sought to kill all the Jews of Europe, Anne was an ordinary girl in an extraordinary time. The events recorded in Anne Franks's diary took place during World war 2. Both prior to the war and throughout the war years, The Nazis continuously depicted the Jews as Sub-human and as vermin.
The Franks family had to go into hiding to avoid getting killed. Throughout the family's time in hiding, Anne kept a diary of everything that happened. Anne retained a positive outlook on life even though she had to remain hiding.
She still believed that in spite of everything that people are truly good at heart. that what is done cannot be undone but that one can prevent it from happening again. in her words "don't think of all the misery but of the beauty that still remains" and that whoever is happy will make others happy too.
Anne Franks believes that no matter what we may be facing, that we should look up to the heavens and everything will be alright and that the cruelty will end and peace will return.
Asking if I will have the same sentiments about human nature; I would say yes. my reason being that we must continue believing in the best even when faced with the worst.
Explanation: