Hi!
I was doing a past paper on a Seneca passage (letter 53 section eight) and the question asked to describe the syntactical structure of the phrase below.
‘somnium narrare vigilantis est’
I am unsure what to say, any help would be greatly appreciated !!! 
This is a nice example of Seneca’s concise and pointed style. First off, context: this is the first half of a statement comparing a bodily “affliction” with vice. Seneca uses comparisons of these elements quite often; in this particular case, Seneca’s point is that one cannot acknowledge his faults while he is in their power; thus, just as one must be awake to relate a dream, to acknowledge a vice is an indication of sanity. As to the syntax, the literal translation of “somnium narrare vigilantis est” is “relating a dream is for one who is awake”. narrare, the infinitive, is the subject and is limited by the possessive genitive, vigilantis, in the predicate.