It was written in a different time so the language and examples are archaic and would look odd now, but the principles are the same. To paraphrase badly, there

It was written in a different time so the language and examples are archaic and would look odd now, but the principles are the same. To paraphrase badly, there's examples along the lines of "So I laid my hat on the desk, asked his girl to fetch us some coffee and said '...so let's name the company after you'. He took the deal.". Following that to the letter would likely get you kicked out (ie. wearing a fedora to a business meeting makes you look like a loon, summoning the nearest woman to fetch you coffee would likely get you a dirty look or a lawsuit) but the underlying principle of giving up credit to the other guy so everyone gets what they want is still a valuable principle. You can't create word-for-word scripts for social interaction as context varies wildly between situations, locations and time periods - but there are underlying principles of interaction that can be modeled and learned, especially by those who are not naturally gifted with communication skills. (Some other fascinating books on this subject: Robert Cialdini's Influence and Eric Berne's Games People Play)