In operant conditioning occurs when the frequency of a behavior increases because it is followed by a desirable stimulus.

Reinforcement is what occurs when a behavior is performed more often because something good happens when it does. This is because creatures are inherently motivated by rewards, and they believe that they can influence situations in their favor by doing the actions that result in the most positive outcome.

Who it was like back then

It is meant that like tapestry scientific theories often need to pull out since they are not relevant and often times the whole chain of theories may be pulled out.