Weep not for him that dieth

[meliss]

It's just for my soul. I found this poem by accident, and it sounds like addressing to me, but it's not traditonal English. What is this method of adding "th" in the words like "dieth", "lieth"? Thank you.

Weep not for him that dieth -
For he sleeps, and is at rest;
And the couch whereon he lieth
Is the green earth's quiet breast:


Weep not for him that dieth

[Tdol]

In older forms of English, the verbs had different endings. The third person used -th, now replaced by -s. However, this is not used consistently here (sleeps, not sleepeth), though at the end of the poem, she does use it:
Blest, blest is he that sleepeth
She also uses 'ye' for you. It's older English, though I think she's using it for effect.