A necessary element of writing or speaking – if it is to be enjoyable and sustained – is to believe what one writes or says, and to express those beliefs as one naturally would. (Even more important, of course, is to hold sound ideas, but here I’m writing about the underlying feeling of expression.)
Writing what one believes, in the style one would naturally speak, is different from writing to please. Some may be persuaded, others not. It’s notable, however, that some are probably beyond persuasion. That’s not surprising; it would be surprising if all people were persuadable.
Gloop stuffed himself with chocolate for much of his young life, and probably had been rebuked for over-eating now and again. Yet, in the film, he just couldn’t stop gorging, at the risk of an accident, even as Frau Gloop recommended moderation in Augustus’s habits (“save some room for later”):
Someone writing to Augustus with words of caution would surely get nowhere: the porcine German boy was willing to eat to the point of calamity. Gloop was gluttonous even as a child. Had he been not a boy, but an adult German chocoholic with many decades of gorging, one could guess he would have, by then, been even more resistant to warnings.
One doesn’t write for Gloop, but of what one believes, and for those who are not yet in the grip of a ravenous craving like the one that held Gloop.