这是个特殊的复合句.(I happened to read for amusement Malthus on Population,)是主句.后面的and多余了.因为being后面是现在分词短语,作伴随状语.而which……是状语中引出的定语从句,修饰 existence.being prapared 有被动的含义吗？没有被动的含义，这时的 prepared相当于形容词。比如说，北方人在冬天，不会受冷就可以说， People in the north will not suffer from the cold becsuse they are well prepared.