future passive imperative of a verb + fuit (perfect active indicative of 'sum') =?

Question

Just to give you some language background from my side, I have not learned the Latin language at all, and my mother tongue is neither English nor any other Indo-European language. I am reading ancient texts already translated either in English or in German, and occasionally I want to check their original words.

Here is the Latin sentence I'd like to read:

Nec vero Pythagoras nominis [scil. philosophiae] solum inventor, sed rerum etiam ipsarum amplificator fuit.
(Cicero, Tusculanae disputationes, V 4)

I have an English translation for it:

Nor was Pythagoras the inventor only of the name, but he enlarged also the thing itself.
(Yonge, Charles Duke)

My question would be, how can I understand the verb construction of "amplificator fuit"? As far as I have checked out from Latin dictionaries, it is future passive imperative of a verb 'amplificato' + fuit (perfect active indicative of 'sum'). First of all, is my understanding correct? If so, can you explain easily how the past tense like 'enlarged' is constructed of a verb "future" passive "imperative"?

Thank you!

Answer 1

Both inventor and amplificator are derived nouns ("inventor" and "expander"), although they do indeed look like future passive imperatives. In my experience something that looks like a future passive imperative is more often something else, although it is good to keep all options in mind.

The main structure of the sentence — which hopefully makes the English translation you cite look reasonable — is:

Not only was Pythagoras an inventor, he was also an expander.