830: Passival (building) Mar 17, 2017

In English, a verb can be either active, meaning—simplistically—that the subject performed the action, as in "I wrote that book" or passive, meaning that the subject has the action performed to it, as in "that book was written (by me)". For a while in English, however, there was the passival, which was a middle voice indicating an action that was progressing grammatically actively but semantically passively. Keeping up with the example before, it would be "the book is writing". The word 'building' meaning, 'something being built' came from this before this grammatical feature was replaced by the progressive passive. Middle voices are fairly rare; Latin writers who could not use a middle voice were quite jealous of Greek's, and went to great lengths to emulate it. It is a shame that this form is now archaic.
If you're curious about other traces of archaic grammatical features, click to see Functions of S