[…] When thoughts Of the last bitter hour come like a blight Over thy spirit, and sad images (8-10)
This poem doesn’t try to pretend that being sad isn’t part of life. After all, we’re talking about death. At one point or another, that idea is going to make just about anyone feel sad. This line gives us a dramatic image of that moment, when you suddenly start to think about what the end might be like. The speaker imagines those sad thoughts as being like a disease, or a plague ("a blight") that attacks your spirit.
Make thee to shudder, and grow sick at heart;— (13)
This is another image of what it might feel like to think about death. The speaker imagines us shaking and feeling sick and awful, full of terror at the thought of death. For the rest of the poem, he’s trying to talk us down a little. He wants us to see how thoughts of death can be calm and almost reassuring, rather than awful and sickening.
[…] in the cold ground, Where thy pale form was laid, with many tears, (19-20)
This is one of the only places in the poem where we get an image of actual people and the way they feel. We spend a lot of time zooming out to the sun, or flying all around the world. In this case, though, we get a quiet little moment. It’s a reminder that, even if death is common and is as old as time, it still hurts when it happens. Bryant makes great use of little details like the "pale form" of the dead body to drive that point home.