They had been spelt backwards on purpose as a sort of code when the light shone though it reflected the words like a mirror image.
(They; had been spelt backwards; ) (the light; shone; T:though it reflected the words like a mirror image) (it; reflected; the words like a mirror image)
They the light it
had been spelt backwards shone reflected
T:though it reflected the words like a mirror image
the words like a mirror image