This post is going to be the Latin grammar equivalent of a YouTube wormhole. You have been warned.
Let’s begin with a simple English sentence. ‘I want to read’. ‘I want’ is a Finite Verb; Finite because it has boundaries. Those boundaries are its Number and Person. Number is simple, Singular or Plural. ‘I want’ cannot mean ‘we want’. It just can’t. Person is a little more complicated. There is First Person (I or we), Second Person (you, you, youse or y’all) and Third Person (he, she, it or they). ‘I want’ doesn't mean ‘you want’. It just doesn't. ‘to read’ is not a Finite Verb. It is an Infinitive Verb. It just does not have the same boundaries. In Latin the entire sentence could be written cupio legere. (note the link between the verb ‘I want’ and Cupid, the God of Wanting).
Now, let’s move on to a second sentence. ‘It is good (bonum) to read’. In Latin this could be expressed bonum est legere. No problem here. Except, if you want to get technical, legere is no longer an Infinitive Verb. It is now a Gerund. And a Gerund is not a Verb at all, but a Noun. It makes sense, because if you were going to swap legere out for another word, it would be a Noun. A temple is good. bonum est templum. In English we can express the Gerund as ‘to read’ (as above) or as ‘reading’. Reading is good.
Now, I know what you are thinking. If the Gerund is a Noun, then surely it must have cases. And you would be right. In the sentence bonum est legere, legere is the Subject of the Verb and therefore in the Nominative Case. What, then, does the Gerund look like in, say, the Ablative Case? It looks like this; legendo. And the Gerund in the Ablative Case is a very useful thing. It can express the action by which something is achieved. For example, linguam Latinam legendo disco. I am learning (disco) the Latin language by reading.
I now want to finish up with a third and final sentence. ‘Do you see the children reading under the tree?’. In this sentence ‘reading’ is neither a Verb nor a Noun. It is a Participle. And a Participle is a kind of Adjective. ‘reading’ is describing the children. And in Latin we could express this as videsne pueros legentes sub arbore?
So legere, legendo and legentes can all be translated into English as ‘reading’ and yet all mean very different things. I bring all this up because today’s page has two Participles in it; praetereuntes (passing by) and custodientem (protecting). The first ends in –es because it is plural (describing people), the second in –em because it is singular (describing Miranda).
It pleases Pico to watch the people passing by. Do you see Miranda, the police officer (public guard), protecting the town?