Sentences of a paragraph are given below in jumbled order. Arrange the sentences in the correct order to form a meaningful and coherent paragraph.
A. There are several factors that contribute to wisdom.
B. Doing this has become more difficult than before owing to the complexity of the specialised knowledge required.
C. This is the capacity to take account of all important factors in a problem and to attach to each its due weight.
D. Of these, I should put first a sense of proportion.