In researching for a paper I'm writing on C.S. Lewis and Mythology, I found an interesting quote, from one of his many letters to children:
"They tell me that one should never try to learn Spanish and Italian at the same time. The fact that they are so alike of course helps one a bit over the meanings of words (but Latin would help you almost equally for both) but it makes confusion in one's mind about grammar and idioms—in the end one makes a horrid soup out of both... By they way good easy Latin reading to keep one's Latin up with is the New Testament in Latin. Any Roman Catholic bookshop will have one: say you want a copy of the "Vulgate New Testament." Acts goes specially well in Latin" (72, Letters to Children, Dorsett & Mead).
Indeed, I find Lewis' advice very practical. The Vulgate is one of the more accessible works in Latin, and is readily available online and in bookstores. Just thought you might be interested.
[UPDATE:] Found some more thoughts on Latin and philosophy (from letters to children) from Lewis:
"To be able to read Latin easily (i.e. without having to translate it mentally as you go along) is an enormous advantage later on. Practice on the Latin New Testament where you know the story already and the style is very simple. Acts goes especially well in St. Jerome's Latin" (73-74, ibid).
[On Cicero:] "Congratulations... on escaping Cicero, who, to my mind, is the greatest bore (except possibly Ben Jonson, Laucelet Andrewes, and Mrs. Humphrey Ward) of all authors whether ancient of modern" (83, ibid).
[On the soul:] "Everything I need is in my soul? The Heck it is! ... Never exaggerate. Never say more than you really mean."