"In such a school moreover, the study of the vernacular and of classical literature will do no damage to moral virtue. There the Christian teacher will imitate the bee, which takes the choicest part of the flower and leaves the rest, as St. Basil teaches in his discourse to youths on the study of the classics. Nor will this necessary caution, suggested also by the pagan Quintilian, in any way hinder the Christian teacher from gathering and turning to profit, whatever there is of real worth in the systems and methods of our modern times, mindful of the Apostle's advice: "Prove all things: hold fast that which is good." Hence in accepting the new, he will not hastily abandon the old, which the experience of centuries has found expedient and profitable."
An article I wrote a long time ago about whether you can use Charlotte Mason and still "Keep in Catholic":
I've heard similar comments in the past, and in fact I think you might find some threads in the archives of CCM on this subject. I personally don't find the evidence I've heard very convincing. I don't have the book you mention, but I have read through most of Charlotte Mason's books at one time or another. Here are some thoughts:
Charlotte Mason's style is not always easily understood by those of us who live in this century and don't have a good sense of the context of her times. When faced with a popular philosophy which has had a heavy influence on the people of her time, her strategy is to depict the philosophy quite sympathetically, listing points of agreement and almost "making a case" for the opposing side, before going into detail about her points of difference. This dialectic technique was quite common in previous centuries -- cf Socrates and St Thomas Aquinas.
For example, in Parents and Education, she writes as she is summing up the impact Rousseau has had upon parents of her time: "Rousseau succeeded, as he deserved to succeed, in awaking many parents to the binding character, the vast range, the profound seriousness of parental obligations. He failed, and deserved to fail, as he offered his own crude conceits by way of an educational code." Her whole section on Rousseau is in this tone. You can find it at the Ambleside website, in the first section of Volume 2 of her works.
There is nothing wrong with finding points of agreement even with someone in ideological opposition to oneself, as Charlotte Mason does throughout her books. In fact, it is an excellent strategy and discipline. That is basically what we ourselves are to do when we are sorting through Charlotte Mason's works, or the works of anyone in our imperfect world. I think that when people "rumble" about CM's "atheism", or "humanism", or "anti-Catholicism" they are often taking a few phrases of her books out of context, much as some fundamentalists take Catholic writings out of context to "prove" that we worship Mary or whatever. It would be better to start as CM does, by fairly pinpointing the *real* areas of difference (assuming
there are any) rather than setting up a straw man to beat down.
Of course Charlotte Mason's books are not to be taken as gospel or the Magisterium, and of course she did not intend them that way. She meant them to be read thoughtfully and critically by fellow educators and intelligent, sincere parents of her time. I think it was CS Lewis who said that every century and era has its blind spots and over-emphases on certain ideas; for this reason it can be very beneficial to read the works of past ages, because we don't necessarily share the same blind spots and are more likely to be able to read discerningly and sort out universal truth from temporal confusion and error.
Rousseau is still with us, I believe -- we just aren't as conscious of his shadow nowadays as CM was back then. So I think that what she writes about him and about other educational philosophers of her time is valuable source material and can shed some light on some of
the issues we deal with even a century or so later. However, it is important to read historical material in context and not "project" our own present struggles and conflicts onto it -- I think perhaps some of CM's critics do a little of this, or perhaps, hold her to an impossibly high standard of infallibility that few of us could achieve ourselves even informed by the mind of our Church.
I hope this helps a little. Again personally, I find a lot in CM's writings that is wise and practical, a little that seems sort of timebound and less applicable, and very little indeed that I would
put a red flag next to, meaning that it is unequivocally harmful. I could see where some of her ideas, like "children are born neither good or evil" could be misunderstood and misapplied, and seem to ally her with secular humanism, but I take that to be in context of opposition to the Calvinist conception that children are born corrupt with no goodness, rather than weakened and compromised by original sin but free from actual personal sin. cf ccc 405 "Although it is proper to each individual, original sin does not have the character of a personal fault in any of Adam's descendants. It is a deprivation of original holiness and justice, but human nature has not been totally corrupted: it is wounded in the natural powers proper to it, subject to ignorance, suffering and the dominion of death, and inclined to sin - an inclination to evil that is called concupiscence."