Here is Leonard Bernstein exhorting a friend to take care, stay alive and write back.  This was even before the war, when the ‘stay alive’ element became more urgent. 

Again, be careful, stay alive, write. 

Source: Leonard Bernstein, letter to Kenneth Ehrman, April 1939, in Nigel Simeone ed., The Leonard Bernstein Letters (New Haven: Yale University Press, 2013), p. 30

Photo credit: Anne Nygård at unsplash