[T]hynges sensibly perceiued: as of a momentanye sounde iterated […].

Unruinated towers.

Now all the children have grown up and left, the house is very quiet.

The learner's selection from his/her store of interlanguage rules is not haphazard but systematic and predictable, based as it is on his/her existing rule system in much the same way as the native speaker bases his/her speech on the internalized knowledge of the L1 system.