Question

quotation
\if people can say, oh! i did not know, i did not mean any harm, they think it is all right.\
\if we could act a little more according to common sense, and a good deal less according to fashion, we should find many things work easier.\
\good luck is rather particular who she rides with, and mostly prefers those who have got common sense and a good heart; at least that is my experience.\
theme
ignorance is not an excuse for doing wrong.

Explanation:

The second quote emphasizes the value of common - sense over fashion for easier work. The third quote associates good luck with those having common sense and a good heart. So the common theme is the importance of common sense.

Answer:

Common sense is valuable.