Answer:
It is a sentence about a universal idea in this passage.
Step-by-step explanation:
Love conquers all may be the theme but the author doesn´t say it directly; at best he/she can say it indirectly via Juanito.
Love = subject conquers = predicate all = object. So it is a sentence.
We don´t know if this is what the story is about; but it is the theme in this passage.