So is Desmond OK now ??

Last episode it appeared Desmond was going out of his gourd. ...Now this
episode he appears completely normal -- at one with the universe.  So
what's the story?

.. Does his conscious cease travelling through time once he finds a
"constant"?  ..And how would that work?   ..Or is his mind zipping
around in his life, but he can accommodate it -- like an alcoholic can
appear normal to those around him?    ..And...  Would he still be
capable of having future flashes?    ..Jon