IF...

If...
the supermarket clerk is a teacher
the Great Enlightened One is a Teacher
a Parent is a teacher
a Friend is a teacher
animals are teachers
organic nature/Nature is a teacher
a school teacher is a teacher
if everyone & everything is a teacher

it is up to - indeed the Work of - the Individual Entity to Unify ALL Teachers, low and high, as ONE Teacher
Then One can see how a Great Master would say that Nature was his only Teacher.
To an Entity like Him, Nature...is EVERYthing...
not just organic nature
but the Transcendences too....