Donald Knuth taught a course at Stanford on technical writing in the 80s. The course notes include the following quotation regarding introductions to books and how people always skip them:
As for those readers who do know how to study my composition, no author can accompany his book wherever it goes and allow only certain persons to study it. - Maimonides
However, there's no reference to where its from (or what translation) and I couldn't obviously find this passage on Wikiquote.
Is this a real quotation? If so, what, exactly, was Maimonides talking about? From other excerpts from the preface to The Guide for the Perplexed it seems like he might be saying "don't blame me if someone ignorant reads this and misunderstands what I'm saying," but I'm not quite sure.
Yes, this is a real quotation, from a letter to R' Pinchas ben Meshulam haDayan of Alexandria. The letter is originally in Judeo-Arabic and has been published in Hebrew translation. To provide some context, the Mishneh Torah (which is the subject of the correspondence) was published as a sort of comprehensive tome of Jewish Law. The tome drew criticism on multiple fronts. Some scholars of the time criticized the lack of citations of earlier halachic opinion. Another criticism, addressed here by the Rambam, is that the accessibility of the Mishneh Torah could lead students to forgo study of the Talmud in favor of the Mishneh Torah. I've provided for reference the rest of the paragraph from which the quote is taken. The letter is published in partial English translation by Isadore Twersky in Introduction to the Code of Maimonides.
In the introduction to my composition, I explicitly wrote that my sole purpose in composing it was to alleviate the burden of those students who because of their impatience of spirit were not able to descend to the depths of the Talmud, and therefore could not understand from it the way of determining what is permissible and what is forbidden: I discussed this matter at great length there. As for your statement about the names of the Tannaim and Amoraim, I already mentioned the names of most of the Sages at the beginning of my composition. Is it in fact the case that anyone who attempts to decide the halakhah and to make (out of the law) a clean fine flour is guilty of desecration of His name, just as has occurred to you? Already before me there were Geonim and other great scholars who composed works and compiled codes, in Arabic as well as in Hebrew, in which they adjudicated the halakhot on given subjects. No one before my time, not at least since the time of Rabbi Judah and the other holy scholars of his period, adjudicated all the halakhot in the Talmud and all the laws of the Torah. Yet that I should be held responsible for desecrating His name solely because my work is comprehensive astonishes me greatly. As for those readers who do not know how to study my composition, no author can accompany his book wherever it goes and allow only certain persons to read it.