so given a (not necessarily lex) left adjoint f from topos t1 to t2, consider ... ??

?? model m1 of t1, and m2 of t2, and ... ???

m1 : t1 -> _set_

m2 : t2 -> _set_

f : t1 -> t2

f*m2 -> m1 ???

???? ....

?geometric relation" .... ???? ...