"The Dead (IV)" opens with a wistful tribute to those who have died and to everything they've had to leave behind. Death, these first lines suggest, means an end to all the everyday loveliness of life: joys so ordinary that one might not appreciate them until they're gone.
Part of the pleasure of being alive, a couple of initial metaphors suggest, is the experience of feeling—and not just feeling happy or satisfied or comfortable, either:
These hearts were woven of human joys and cares,
Washed marvellously with sorrow, swift to mirth.
The human "heart," these lines suggest, is all the richer for experiencing the "joys and cares" that are "woven" tightly together. And it's not weighed down by "sorrow," but "washed marvellously" with it, rinsed miraculously clean. Not only is "sorrow" marvelous, but it also travels pretty close to "mirth" (or laughter).
The joy of life, in other words, isn't just in the good times, but in the total package of human experience, joy and sorrow together.
There's a similar sense that just being alive is a blessing in these lines:
[...] Dawn was theirs,
And sunset, and the colours of the earth.
Living on this planet offers the chance to relish the everyday glory of sunrise, sunset, and the "colours" the sunlight illuminates.
What's more, life offers the chance to grow and to develop wisdom. "The years had given them kindness," the speaker remarks: the "dead" the poem addresses had learned something from their joys and sorrows and sensations.
These first lines, then, paint ordinary, unexceptional life as a lovely gift. In context, this idea feels awfully poignant. This poem is a tribute to "The Dead," to those who no longer get to enjoy all the richness these words describe.
What's more, it's part of Rupert Brooke's "1914," a five-poem sequence honoring the fallen soldiers of World War I. While the poem speaks of "the Dead" more generally, the speaker might have in mind a particular group of the dead, the young men whom the Great War ate up in such terrible numbers.