Dillard: 

" Unfortunately, nature is very much a now-you-see-it, now-you-don’t affair. A fish flashes, then dissolves in the water before my eyes like so much salt. Deer apparently ascend bodily into heaven; the brightest oriole fades into leaves.” 

Whitman: 

Nor any more youth or age than there is now,"

Thoreau: "Time is but the stream I go a-fishing in. I drink at it; but while I drink I see the sandy bottom and detect how shallow it is. Its thin current slides away, but eternity remains."