How to use 以 in Literary Chinese? For example:   


  差之毫厘，谬以千里


I understand the overall meaning of this saying, but if I wanted to just be able to define 以 as it is used here, how could I do so?
以 = as; using; taking.

差之毫厘，谬以千里 = to miss by a hair is as wrong as (to miss by a) thousand li, or more to the point: miss by a hair, but (still) be off a mile.