Why does switching the current flows in any two phases reverse the direction of rotation of a stator's magnetic field?

in three phase motor if we want to change the rotation we have to change two phases between the three phase supply 

The rotating magnetic field of the stator is created from a system of 3 coils spaced in the space of 120 ° and traversed by 3 currents phase shifted in time by 120 ° (Ferraris theorem). The direction of rotation of this field is given by the order of these phases, so inverted two of the three phases automatically reverses the direction of the rotating field.

Phase angle between 3 phase120 degree  and current flow for the L1 L2 L3 for example clockwise rotation, and our magnetic field also clockwise rotation, if we change any two phase, our current flow also changing to anticlockwise rotation,and our magnetic field was rotating by anticlockwise rotation