This is from a dialogue in the film Gladiator (2000):
We mortals are but shadows and dust. Shadows and dust, Maximus.
Source: Gladiator (2000) movie script - Screenplays for You
Could someone please explain this sentence? Apparently, the words “dust” and “shadows” are used figuratively. Does this “but” mean “only”?
"but" in your example is an old expression equivalent to "nothing but". Here are some examples of use:
I hear of your tricks; you disown me for your mother, and say I am but your nurse. Is not this true?
Well, say the holy Scriptures of Truth, there is but one God.
in respect to which all these glories are but smoke, all these riches are but dirt, all these delights are but dreams, all these businesses are but triflings, ...
In your example, Maximus is simply stating that human life is ephemeral. The word shadow is used as a reference to Plato's cave and the word dust may be a biblical reference:
Genesis 2:7 - And the LORD God formed man [of] the dust of the ground, and breathed into his nostrils the breath of life; and man became a living soul.
Ecclesiastes 12:7 - Then shall the dust return to the earth as it was: and the spirit shall return unto God who gave it.
And here, you can see the decline in use:
"but" can be a conjunction expressing contrast as in: He was sad, but didn't show it. And it can be an adverb meaning only, not more than as in There were but three people present/She is but a little girl, not a woman.
Furthermore, "but" has a lot of particular uses as shown in a larger dictionary.
It means that
we are nothing. We're just a bit of dust resting in the corner. We're just a shadow passing through. We won't be remembered. That's how little bit of space we take up.
