My understanding is that there aren't many pairs of intransitive and transitive verbs in modern English. Off-hand, I know of three (though I think there are more):
- lie vs lay
- rise vs raise
- fall vs fell
There are of course verbs which can be both on their own without a sound change, but I'm not interested in those.
The question then is, did we ever have more of these pairs such that they simply fell out of use over time? Or did we only ever have a small amount?
If we did lose them, about which generation of English did we lose them in?