one morning two brothers set out on a journey together.
at noon they came to a forest and decided to lie down there
for a while and take a nap. when they woke up, they saw a
stone lying next to them. there was something (written on
the stone), but it was not very clear. they tried to make out
[what the writing said].
“whoever finds this stone,” they read, “should go straight
into the forest at sunrise. he will come to a river (that flows
through the forest at the foot of a mountain). he should
swim across the river to the other side. there he will find a
female bear and her two baby cubs. he should take the cubs
from the mother bear and run up the mountain with them
without looking back even once. on the top of the mountain,
he will see a house, and in that house he will find
happiness.”
when they had read what was written on the stone, they
sat in silence for a while and thought about what they should do.

위문장 에서요 빨간색으로 칠한 부분이 이해가 안가는데요.. when thet had read는 대과거로 쓰고
sat은 과거로 쓴이유가 뭔가요..? 따지면 그들이 돌에써진걸 읽은때나 고요히 앉아 있었을때나 그게 그거 아닌가요..?

여기선 다르다고 봐야하나요..?