If your thought is worth anything, you can afford to laugh at some small violation of grammar, or the knocking over of some finical standard or other.

Not that I would be thought to advocate either carelessness, laziness, or indifference in speech.

Quite the contrary, as all who have heard me speak well know.
But I fully believe that _thought_ is of greater importance than _form of expression_.

And, as for grammar, I believe with Thomas Jefferson, that "whenever, by small grammatical negligences, the energy of your ideas can be condensed or a word be made to stand for a sentence, I hold grammatical rigor in contempt." I was present once when Thomas Carlyle and a technical grammarian were talking over some violation of correct speech--according to the latter's standard--when Carlyle suddenly burst forth in effect, in his rich Scotch burr: "Why, mon, I'd have ye ken that I'm one of the men that make the language for little puppies like ye to paw over with your little, fiddling, twiddling grammars!" By all means, know all the grammar you can.

Read the best of poets and prose authors to see how they have mastered the language, but don't allow your life to become a burden to you and others because of your worry lest you "slip a grammatical cog" here and there, when you know you have something worth saying.