Including the title, the word death appears in "When Death Comes" five times! It's referenced directly, though not by name, several more times. If you wanted to sum up the basis of the poem to a friend you could probably just call it a meditation arising from the thought of death. Of course, death only means something in combination with life, which could also be called our speaker's main concern. Much of the work of this poem seems to be challenging the idea of death as something to be feared, seeing death instead as a way of defining how we live, and as something to be approached with the same sense of wonder and possibility that makes us appreciate life.
The poem opens with the repeated phrase "when death comes" and ends (the second and third to last stanzas) with the repeated phrase "when it's over," with "it" referring to life. This transition demonstrates the arc of the poem, which transforms a contemplation of death into a contemplation of life.
In order for the speaker to consider approaching death without fear, she needs the possibility of eternity. Thus, the only way she can handle death so calmly is by transforming it into something else, a cottage of darkness where life can, in some way, continue. She does not overcome her fear, but rather convinces herself that death is not in fact death.
In speaking of both life and death, images from the natural world (bear, iceberg, field daisy) are central to the way the speaker communicates in "When Death Comes." For her, the natural world is not only an avenue through which we can (and should!) observe these forces at work, but it's also our home, since we are part of "a brotherhood and a sisterhood" of living things. We get the feeling that, when the speaker compares each life to a flower, part of what she's doing is putting all forms of life on equal footing (whether flower or person or fish), telling us, in another way, something that she declares a few lines later – that "each body" is "something precious to the earth" (lines 19-20).
By comparing each life to a flower, and declaring each body precious, the speaker makes an argument for the equal worth of all living things.
As seen particularly in the image of the bride and bridegroom, and the last line of the poem, the speaker longs for a stronger connection to the world, which she hopes to accomplish by examining the world until the name of each thing is "a comfortable music in the mouth."
Curiosity and amazement are a couple key words in our speaker's description of her ideal approach to the world (and her approach to death). The vividness of her opening descriptions of death in "When Death Comes" demonstrates a keen attention to detail and also an appreciation of the strangeness and vastness of the forces at work in the world. We feel that a good way to sum up our speaker's philosophy would be: approach everything with a sense of awe, for there will be something amazing going on if you just pay attention.
Through her many vivid depictions of death, our speaker is expressing a form of awe at both the vastness of death, and also its intimacy through the specific and tangible forms it takes.
For our speaker, the main business of living seems to be to approach each part of the world with a sense of wonder, whether that part of the world is a person, a daisy, or even death.
In a poem that spends a great deal of time contemplating death, we would expect fear to be a big part of it. Death is scary, right? If you like life, doesn't that mean you dislike and fear death? Well, fear is certainly a part of "When Death Comes," and the images we see of death are fairly scary. But our speaker's impulse is actually to move in the opposite direction. She does love the world, but she wants to approach death with the same curiosity and interest as she does life. The suggestion is that perhaps death is another part of life, not something that is necessarily an end, or to be feared.
Our speaker connects being curious and embracing the world with living well and being able to face death without fear. She suggests, then, that fear comes from being distant from the world.