The companion book is addressed at native speakers of English (OK, amongst others), but it surprises me that it doesn’t make use of the fact that we all understand (to an extent) the way English grammar works and the similarity of same to Latin grammar. I’m thinking modals with infinitives, as an example. Or am I mistaken?
Opinions?
Paul.
Would that we all did understand the way English Grammar works!
Often latin works differently to English. What exactly did you have in mind? The discussion of say posse on p.221 is an example where usage is different.
I found the word modal used in a Spanish page https://linguaeantiquae.wordpress.com/2014/04/19/el-verbo-sum-y-sus-compuestos/
And in this English page: https://quizlet.com/gb/231605978/nolo-volo-and-possum-latin-modal-verbs-flash-cards/
This one over my head: https://www.academia.edu/4023007/_The_Latin_Infinitival_Structures_with_Modal_and_Aspectual_Verbs_
https://www.degruyter.com/document/doi/10.1515/9783110678222-004/pdf
Not really trying to make a point here, just curious as to why I never see the word in that book.
I am sorry I cannot give you a full response.
I wonder what would be gained at a beginner’s level from a general discussion of “modal” verbs. As I said in my first post the companion illustrates how “posse” (a modal verb) can be used differently in English and Latin (p 221).
Because English modal verbs are often used to express the subjunctive in Latin and are also used when there is no subjunctive in Latin I think introducing the concept would lead to more confusion rather than clarity.
I also don’t see why one needs the term in eg the Spanish link describing the use of sum in periphrastic constructions. The periphrastic perfect is passive in latin isn’t it active in Spanish? Modal in this context means little more than “auxiliary verb”?
I am all in favour of using terminology with which students are familiar to explain Latin but this seems a complication we can do without.
Others with greater linguistic knowledge might be able to provide insights or corrections.
I just skipped forward to 221. I’ll revisit it when I get that far 
I was referring to the simple fact that modals don’t work alone and need an infinitive. My wife was teaching TEFL and had to mention the modal “concept” very early on with her students.
The word “modal” (along with auxilliary) is just a word, but to name a category of verb that needs a partner. That is simplifying it a tad, but it’s a simple concept to understand for a learner, IMHO. Obviously English, Latin and Spanish all go off in different directions, but I’m just talking about a simplistic concept that pretty much applies across boundaries.
It would seem that others see this quite differently to me. I’m OK with that
Paul.
Paul, I dont want to be unnecessarily complicated but I don’t think in Latin you can say that modal verbs “need an infinitive”.
Velle works with an infinitive construction see Gildersleeve 532 but it can also take an ut plus subjunctive clause Gildersleeve 546.
I hope you are surviving the heat wave if its affecting where you are. 
Heh. Obviously I meant that the “comparison” may be of use up to the stage I’m at. I can just “see” it easier like that. It would seem that as I move on, I shall have to leave that little comfort blanket behind
Cheers.
Paul.
My Gildersleeve has a long section about auxiliary verbs and the infinitive.
https://www.google.com/books/edition/Gildersleeve_s_Latin_Grammar/UU0BIAbE0SIC?hl=en&gbpv=1&pg=PA276
It’s worth clicking through for the categorized list of verbs. He does mention in note 4., verbs of Will and Desire take ut as well as the Infinitive.