Why is python not written in C++ ?

[Lawrence D'Oliveiro]

In message <i3bseh$kfm$1 at reader1.panix.com>, Grant Edwards wrote:

> The problem has nothing to do with the relative merits of the
> languages.  The problem is inertia.

So how was C++ able to get popular in the first place? And how was Java able 
to grab some share from it?