*Revision*
Proof:
Given the point P,and the distinct non-collinear points A,B,C.
By Prop. 2.2, <->AB,<->AC, and <->BC are concurrent.
Suppose P is equal to either of the points A,B,C, say A. Then <->BC
does not pass through P. The other two cases are easily verified.
Suppose P is distinct from A,B, and C. Then by I-3 at most two
of the lines <->AB,<->AC, and <->BC pass through the point P.
[#]
I am still unsure about this proof. Mainly the third part and the use
of 2.2.