  The Universal Seesaw pattern coupled with a Light$\leftrightarrow$Heavy
symmetry principle leads to the Diophantine equation $\displaystyle N =
\sum_{i=1}^Nn_i$, where $n_i\geq 0$ and distinct. Its unique non-trivial
solution $(3=0+1+2)$ gives rise to the geometric mass hierarchy $m_W$,
$m_W\epsilon$, $m_W\epsilon^2$ for $N=3$ fermion families. This is realized in
a model where the hybrid (yet Up$\leftrightarrow$Down symmetric) quark mass
relations $m_d m_t \approx m_c^2\leftrightarrow m_u m_b \approx m_s^2 $ play a
crucial role in expressing the CKM mixings in terms of simple mass ratios,
notably $\sin\theta_C \approx {m_c\over m_b}$.
