…from its cover—a point of view widely used. This proverb implies that we should not make opinion of someone out of his/her physical appearance (or alternatively, first impression). I’m not against this idea, but I have other points of view regarding this.
Think of this: nobody judges a book on page 227. People will start building their opinion of you on the third or fourth interaction. That includes judging your appearance, gesture, and way to talk. You better make the best impression if you want someone to like you.
Again, think of this: nobody judges a book on page 227. People will not read a whole book before comparing it to another book. They will simply take sample of the first pages, including cover. That’s why we should learn design, literature, and presentation.
Besides, aren’t people today judge a book from the paragraph in the back?