The early scientists of the Royal Society wrote with a delightful clarity and simplicity, their prose looking towards that of our own day. Their punctuation, however, clung to an older rhetorical system, which has disappeared for ever. Whole manuals are now devoted to the craft, crammed with pernickety details which however handful to the printer and typographer, leave the average writer unable to see the wood for the trees. The whole idea of punctuation is to make things clearer and easier for the reader. If readers know the meaning of the words they read and yet find themselves stumbling over the full sentence, you can be sure the punctuation has been at fault.
Good punctuation is a series of signals that keep the reader on the right track.
One mark of good writing is that readers are not even aware of the punctuation unobtrusively steering them in the right direction. First the principles. There are four main types of punctuation. Let's call them the stoppers, the linkers, the intruders and the intoners. They all have different jobs.