From De Rerum Natura (Rolfe Humphries translation):
Or is this
More probable?–that in a single time,
No longer than it takes an eye to blink
Or mouth to utter half a syllable,
Below this instant, this split-second, lie
Times almost infinite, which reason knows
As presences, and in each presence dwells
Its own peculiar image, all of them
So tenuous no mind is sharp enough
To see them all, must focus, concentrate
On only one, so all the rest are lost
Except the one mind has determined on.
Mind does prepare itself, and hopes to see,
Anticipates the next successive image,
And therefore finds it, as it must.
Lucretius seems to have had something of a short-attention span; a page after this he’s offering a preview of Darwin and tearing apart Aristotle’s causes. Most of De Rerum Natura is more metaphysically oriented, but I noticed this little passage, which seems to be very much tied to apprehension.
Lucretius draws on the Presocratics a fair amount; his atomism and materialism draws on Empedocles, and here there’s a bit of Zeno. The question of the mind imposing structures on empirical data wasn’t new, but the emphasis is on paying attention not to aspects of a moment, but to one moment out of many, and from first principles inferring the causality of the next moment (and all those in between).
The continuity of time, then, is assembled from fenceposts taken by the attention of the mind, which, like attention, are not arbitrarily chosen. The sequence of anticipation to a necessary finding of the anticipated moment seems to imply that the flow of time was not as fundamental as Lucretius’s eternal atoms; rather, it’s something that the mind participates in.