What did Pascal mean: 'A vapour, a drop of water, suffices to kill him'?

Question

_{Source: p 29 (Top), Introducing Philosophy for Canadians: A Text with Integrated Readings (2011 1 ed).
Primary Source: Fragment 347, Pensées by Blaise Pascal}

L’homme n’est qu’un roseau, le plus faible de la nature; mais c’est un roseau pensant. Il ne faut pas que l’univers entier s’arme pour l’écraser : une vapeur, une goutte d’eau, suffit pour le tuer. Mais, quand l’univers l’écraserait, l’homme serait encore plus noble que ce qui le tue, parce qu’il sait qu’il meurt, et l’avantage que l’univers a sur lui, l’univers n’en sait rien.

Is the bolded allegorical, and not literal?

My conjecture: Was Pascal referring to water conflicts?

Answer 1

I will try to paraphrase (not literally translate) what the quote says:

First sentence: Thesis.

Man isn't as fragile as rose, a self-sufficient being, but even more, so that he can be brought out of his equilibrium by such simple phenomena as vapour or a drop of water, because he has to think about it.

Second sentence: Explication.

He (identified with his thinking!) has to evolve, include every single phenomenon into the framework of his thinking, and therefore his self-conception is always endangered by the universe (read: nature/phenomena) to be challenged and eventually "crushed". Man then has to reinvent himself, the old self is killed, and a new, more noble one, is born. But in the end, it is man how "kills" himself, not nature.

The link out of the comment of @MauroAllegranza pretty much contextualises this historically as I understand (only six years french in school, maybe I got all wrong ;).

Therefore, the violability allegorically expressed in the first sentence is nothing more than the other side of the medal of "Toute notre dignité consiste donc en la pensée." - All our dignity consists therefore in the thinking. - The sentence following your quote within the very same Pensée, leading to a notion of morals. It is our source of nobility to cope with the universe in thinking, always throwing over our obsolete self-understanding.