Thus, even once philology ceases to be primarily interested in manuscripts, and becomes concerned with different sorts of comparison - let us call it "the historical experience", a "true philological" approach may be defined as an art: involving both an appreciation of rules as well as the readiness to descend into the complexities of myriad particularities, collecting and comparing. Housman writes that a nascent flair for this art is desirable - and we may note that Auerbach was praised for possessing just such a gift. Also important, however, is the habit of thought, which, while no substitute for an aptitude for textual criticism, can minimise error, Housman writes.
This approach is not a science. To illustrate, Housman considers rules vs. examples, methodically arguing that it is the weight of what appear to be exceptions to rules, and not their number, that must, on a case-by-case basis, be "ascertained by classification and scrutiny". It cannot be a science, because its subject matter is the product of the fallible (not hard-and-fast) human being:
It deals with a matter not rigid and constant, like lines and numbers, but fluid and variable; namely the frailties and aberrations of the human mind, and of its insubordinate servants, the human fingers. It therefore is not susceptible of hard-and-fast rules. It would be much easier if it were; and that is why people try to pretend that it is, or at least behave as if they thought so. Of course you can have hard-and-fast rules if you like, but then you will have false rules, and they will lead you wrong; because their simplicity will render them inapplicable to problems which are not simple, but complicated by the play of personality.This is the lesson of what the humanities, as opposed to the sciences, can share. We are to remember human fallibility, and appreciate that science is not the best tool for more accurate understandings of things human. Of course, this is not just the idea of the philologist - although it is fascinating to me that it is possibility the influence of the philologist (Auerbach) that shaped Gadamer's philosophical magnum opus Truth and Method, for making this very point (we remember, too, that he briefly opined in the book that he had not written it sooner to argue against false objectivism in a timely fashion). This idea of the trickiness and case-by-case discernment of the human experience is part of Plato's Socratic elenctic questioning, dialectics.
To shorthand a conclusion to this post, I will refer yet again to how Jowett describes Plato's Phaedrus as a "picture, not a system". What is more, he notes that Plato "works freely" in his writing, meaning, "which is the warp and which is the woof cannot always be determined". Science is not appropriate here: knowledge is reached through "many preparations and oppositions, both of the characters of men and aspects of truth, especially of the popular and philosophical aspect; and after many interruptions and detentions ... we arrive at ... knowledge. This is an aspect of truth which was always lost almost as soon as it was found, and yet has to be recovered by everyone for himself who would pass the limits of proverbial and popular philosophy," Jowett writes.
Finally, as an educator in today's world, I would like to point out the ubiquity of the popular - with its watered-down platitudes, laid down like (psuedo-) scientific law, like: do what it takes to get where you want, which is hardly an ideal civic ethics. In contrast to this, is Auerbach's retort to accusations that he was not methodical enough in Mimesis, and bogged down in too many particularities to be appropriately scientifically philological: "If it had been possible, I would have avoided all general terms and instead suggested ideas to the reader by the mere presentation of a sequence of passages".
Neither catechism nor multiplication table, textual analysis requires engagement of the individual in a case-by-case evaluative dialectics if one cares even the slightest about the truth of the matter (and has a flair for it: cf. can discernment be taught?)
Book in background: Boucher's 20,000 Years of Fashion. Brush: Ewansim via Deviantart.
 cf., "The MSS. are the material upon which we base our rule, and then, when we have got our rule, we turn round upon the MSS. and say that the rule, based upon them, convicts them of error. We are thus working in a circle, that is a fact which there is no denying; but, as Lachmann says, the task of the critic is just this, to tread that circle deftly and warily; and that is precisely what elevates the critic's business above mere mechanical labour."
Post Script: at some point, I will need to change the labels of these posts. In preparation of that, and to that end, for my convenience, I am linking here to all posts I was able to find that mention Gadamer's Truth and Method: experience-experiment; interiority-nonsense; facts-of-fiction; hands-of-tongue; beyond-myth.