I'm seeking for a book which contains several fragments of the medieval philosophical works, literally translates them and explains the obscure points for who wants to improve his Latin.
A good intro book would indeed be a big help. I don't know of one myself, but I do know that there is a lot of interest on Thomas Aquinas on the net. Googling "aquinas latin for beginners" or some such might yield a few leads.– FigulusMar 21, 2020 at 18:02
Out of curiosity, I followed my own advice, and I found some references to A Lexicon of Saint Thomas Aquinas by Roy J. Deferrari. The blurbs make it sound like it might be suitable. Since it's so expensive, you might request a copy through interlibrary-loan and see whether it is worth buying.– FigulusMar 22, 2020 at 18:39
The following book is a good start. It doesn't have literal translations, but it does provide a lot of vocabulary and grammatical guidance.
Reading Medieval Latin by Keith Sidwell
From the blurb:
"Reading Medieval Latin is an introduction to medieval Latin in its cultural and historical context and is designed to serve the needs of students who have completed the learning of basic classical Latin morphology and syntax. (Users of Reading Latin will find that it follows on after the end of section 5 of that course.) It is an anthology, organised chronologically and thematically in four parts. Each part is divided into chapters with introductory material, texts, and commentaries which give help with syntax, sentence-structure, and background. There are brief sections on medieval orthography and grammar, together with a vocabulary which includes words (or meanings) not found in standard classical dictionaries. The texts chosen cover areas of interest to students of medieval history, philosophy, theology, and literature."