threads only called once?

[Ian McMeans]

Can threads only be called once?

>>> myThread.start()
run was called
>>> myThread.isAlive()
0
>>> myThread.join()    # returns instantly
>>> myThread.start()
Traceback (most recent call last):
  File "<interactive input>", line 1, in ?
  File "F:\Python22\lib\threading.py", line 384, in start
    assert not self.__started, "thread already started"
AssertionError: thread already started

Why can't the thread be started again if it's not alive (ie not running)? Am
I missing something here?