He didn't give it, but I attempted to come up with one myself. Here are the axioms
for vectors u,v,w in a vector space V and numbers a,b in a field K:
1) u + v = v + u
2) (u+v)+w = u+(v+w)
3) There is a zero vector O s.t v + O = v for all v
4) for every v and every O, there is an...