Mountain Goat wrote:
Flies do think fast, so is that why flies represent quick thinking? She thinks faster then flies do?
I just googled it and found this
Quote:
'In the 19th century, to say that "there are no flies on him" of somebody meant that the person was alert and active, probably by allusion to cattle that move around enough to deny flies a landing place.'
this
Quote:
One is wide awake; there is nothing slow or dull about one. For example, She may be new to this field, but there are no flies on her. This slangy expression, which alludes to flies settling on a sluggish animal, was being used in Australia in the 1840s but did not appear in America until the last decades of the 1800s.
and this
Quote:
Definition of no flies on
chiefly British, informal
—used to describe someone as quick to understand things and not easily fooled