A diff moves flesh like human bones,
a metaphor for weasels:
well greased, it glides us over ice.
Left still, it freezes.
.
Weasels were the machines taken to Antarctica to replace huskies for traversing. There is an epic story of the weasels of Antarctica, which you can hear from the different people who have worked with them.
Huskies were valued highly by the early expeditioners, for both practical and emotional reasons. Comparing the animal with the machine was a continuing topic of conversation in Antarctica when the weasels arrived in the 1950s.