Sciences in the west didn't just come out of the blue. Most educated Chinese converted to western culture have a naive view regarding the legacy of western sciences. Often in awe of their visible effects today, tracing back to the Greeks a little, then happy with stopping there, and they always forget that the Greeks had to learnt from the Egyptians to become inspired for their subsequential creations too.
However, when Fang started to "think", he fell for the same trap - oversimplifying things. Therefore he was still not truly inspired by what he had just witnessed.