  We present a simple proof of the stability of the hydrogen molecule
$(M^+M^+m^-m^-)$. It does not rely on the proton-to-electron mass ratio $M/m$
being very large, and actually holds for arbitrary values of $M/m$. Some
asymmetric molecules of the type $(m_1^+m_2^+m_3^-m_4^-)$ are also stable.
Possible applications to molecules containing antiparticles and to exotic
hadrons in the quark model are briefly outlined. Revtex Version 3.0, 4 Figures
available on request by Fax or Mail.
