The following lines were lifted from a conversation between Tess Durbeyfield and Angel Clare, the two main characters of Thomas Hardy's greatest novel, Tess of the d'Urbervilles (1891)
Tess: “The trees have inquisitive eyes, haven’t they?—that is, seem as if they had. And the river says,—’Why do ye trouble me with your looks?’ And you seem to see numbers of tomorrows just all in a line, the first of them the biggest and clearest, the others getting smaller and smaller as they stand farther away; but they all seem very fierce and cruel and as if they said, ‘I’m coming! Beware of me! Beware of me!’. . . But YOU, sir, can raise up dreams with your music, and drive all such horrid fancies away!”
He was surprised to find this young woman—who though born a milkmaid had just that touch or rarity about her which might make her the envied of her housemates—shaping such sad imaginings. She was expressing in her own native phrases—assisted a litte later by her Sixth Standard training—feelings which might almost have been called those of the age—the ache of modernism.
Tess is working as a milkmaid because that's the best job she has been able to find; Angel Clare is a gentleman who happens to be working on this farm in order to learn how to be a gentleman-farmer— much to the disapproval of his high-toned ecclesiastical family. The word 'you' in the second line does not refer to Angel who has yet to learn, as Tess has learned, to fear the future; that 'you' is generalized: it refers to all of us, but especially to her who, having born a child out of wedlock, doesn't dare attract attention to herself by using the first-person, singular, pronoun.
Though the second paragraph begins with Angel's surprise at hearing such a talk from a milkmaid, the second sentence ("She was expressing in her own native phrases . . .") could only have come from Hardy himself. Angel Clare could not have come up with a phrase like the "ache of modernism" because he has yet to feel it; nor could he have understood Tess's "sad imaginings" as any other than her own; certainly not "those of the age." (Angel Clare considers himself a free spirit but when Tess finally finds the courage—encouraged by his own confessions—to tell him her story, he turns into a cold, hostile, self-righteous prig and abandons her to her fate, whatever it may be.)
What, in 1891, might Hardy have meant by 'modernism'? Something like a way of thinking characteristic of 'modern' times. And 'modern'? Not 'modish' or 'fashionable', which is how Rosalind uses it in As You Like It; by 1891 the word 'modern' was beginning to take on the sense of 'modernity' as a historical development without precedent: different not in degree but kind from all that had preceded it. And what is it about modernity that makes us ache? For Hardy, it was all about deep time, of tomorrow and tomorrow and tomorrow, as Tess imagines the future, "all in a line, the first of them the biggest and clearest, the others getting smaller and smaller as they stand farther away"; but the past as well, with all our yesterdays growing smaller and smaller until they vanish beyond recall, so that the present moment which is all we've got becomes infinitely tiny, evanescent, and precious.
Again and again, in Hardy's novels and poems, we become aware of the absolute oblivion that swallows us up as soon as we die—obviously, Hardy had no illusions about an after-like—which makes especially poignant the beautiful poems he wrote about his estranged wife, Emma, after she died (in 1912)—as if, having more or less ignored her for years, he wanted to do all in his power to keep something of their love alive and precious for as long as possible. That was 100 years ago and we're still reading and, it may be, aching, over those poems. See, especially, "The Going," "The Voice," "After A Journey," "At Castle Boterel," "The Phantom Horsewoman."
Should you like these poems, there are a lot more: Hardy wrote almost 1000 poems during his long life (1840-1928) and many, many of these are worth reading. But working your way through this huge body of work is not easy. Claire Tomalin's excellent biography is helpful.
Here's a late poem I like—four lines long, it may be Hardy's shortest poem:
Christmas: 1924
"Peace upon earth!" was said. We sing it,
And pay a million priests to bring it.
After two thousand year of mass
We've got as far as poison gas