Authenticity in a work of art—and this is actually a tautology because only works that are authentic are art—is the measure of wether or not the work reflects the author’s authentic self, the authentic self being the person’s complex of real values, not the values they display in society in order to conform. In other words, an authentic work is built around the things its author actually cares about and reflects their real view of the world, not the things they are merely interested in or pretend to care about. An authentic work is an expression of their values.
Is style a part of an authentic work? Proust believed style to be a quality of vision, concluding the following in his explanation of Swann:
Style is not at all an embellishment as certain people think, it is not even a matter of technique, it is—like colour with painters—a quality of vision, the revelation of the private universe that each of us can see and which others cannot see. The pleasure an artist affords us is to introduce us to one universe the more.
Style is an expression of aesthetic value, a judgement passed on the arrangement of the material word into forms one considers beautiful. It is an inseparable part of that complex of values that make up the self. Because it differs from ethical value, it is possible for a work to be authentic despite its style, at least if style is not in any way the integral part of its content. For example, architecture is inseparable from style because the style is itself the representation of the building, a music of stone and steel. Prose that deals with a moral issue can be treated in a variety of styles, may suffer from bad grammar and spelling, and may even be sporadically incoherent, but as long as the idea lives and is communicated to the reader, its content will remain authentic and will be a true reflection of the author’s self.
Style is, simply put, an expression of taste. Taste is something acquired, not something you are born with, being a form of aesthetic experience, i.e. an acquired sight for the little details in an object of your interest. Good taste, when acquired, can be applied to the style of your own work, which in turn communicates it to the reader or observer. While style is not the measure of most works, at least not prose, it is an inseparable part of them, and a good style will elevate a work by presenting its ideas through a developed form, a form that is to leave its mark on the mind of the reader.
The worst thing the author can do is attempt to cripple their style for the sake of an imaginary reader, which will not only degrade their own taste but will also rob the reader of having the chance to experience it. I mean, of course, all the typical advice about simplifying your writing for the sake of improving comprehension. Clarity must always be pursued—you cannot be too clear, although your writing can be repetitive, which is a fault of style and not of clarity—but since good style must necessarily also be clear, it does not make sense to change it for the sake of making your writing easier to read. Thus, careless attempts at “simplifying” prose tend to, unintentionally, degrade its style also. It’s not the size of the sentence, but its structure, that makes it easy to comprehend. It’s not the style, but the material presented, that makes it easy to understand. Beautiful form must always be coherent—which is itself the definition of beauty: a harmonious arrangement of parts—so good style can never be simplified if it is indeed truly good.