I may be off here, but here's my two cents:
Thrust of a jet engine is caused by a whole lot of mass x acceleration which produces a force. So the goal is to accelerate the air. In supersonic applications the problem is that in order to keep the jet engine going, you first need to slow the air down to below M=0.7 (or thereabouts) in the inlet to avoid surges, stalls etc. The engine can then add energy and a bit of mass (think fuel) to this airflow but if we are talking about high Mach numbers then the resulting exit speed may actually be slower than the aircraft's current speed, and this causes the 'engine to drag on its mounts' as mentioned in your book.
Afterburning can help in this respect as it adds mass, but more importantly heats it up considerably. This causes the air to expand rapidly but as it is moving through a confined tube, the end result is rapid acceleration of this mass of air, and that is what we were after all along. After all it is the increase in speed between entry and exit which causes thrust. The 'inducing flow' then refers to the main engine delivering an airflow to the afterburning section, which is its main task at this point.
There are some side effects which I've overlooked here, such as the pressure rise in the inlet caused by the slowing down of the air mass which also produces thrust, but that's not what your question was about I think.
Hope this helps, or have I just added another wrong end to the stick...