Now we must praise heaven-kingdom's Guardian (1)
Heaven is not just some location in the sky; it's a true kingdom, governed and protected by its ruler.
the Measurer's might and his mind-plans (2)
By calling God "the Measurer," Caedmon underlines his precision. It implies that before God starts out on one of his creative projects, he measures first and works according to his "mind-plans."
He first created for men's sonsheaven as a roof (5-6)
This simile comparing heaven to a roof also points up God's love of order. A house with no roof is disorderly—rain and spiders can get on the carpet.