I already did.
There is no "external" and "internal" but the "right way to do thing" and the "wrong way to do thing". Even the right way to do thing such as to let your body to push your arm will need to be modified in combat in order to gain speed.
Let me borrow Adam Hsu's definition here.
http://imageshack.us/a/img534/2232/internalb.jpg
Translated:
The word "internal" was invented by a none TCMA guy (a scholar) Hwang Zung-Si at the end of the Ming dynasty.
External is a term to look down upon others. At the end of the Ching dynasty, XingYi and Bagua guys treated every other styles as "flower fist". Later on they accepted Taiji as one of them. ... Nobody want to be "external" ... The difference between external and internal is not the difference between styles but the difference between training level ... Every style when you started it, you are training external. When you get into detail, you are training internal ... Since all TCMA systems take this path, there is no such thing as "internal" and "external".
Adam Hsu and I share the same views on this subject.