  An algebraic version of a theorem due to Quillen is proved. More precisely,
for a ground field k we consider the motivic stable homotopy category SH(k) of
P^1-spectra equipped with the symmetric monoidal structure described in
arXiv:0709.3905v1 [math.AG]. The algebraic cobordism P^1-spectrum MGL is
considered as a commutative monoid equipped with a canonical orientation. For a
commutative monoid E in the category SH(k) we identify the set of monoid
homomorphisms from MGL to E in the motivic stable homotopy category with the
set of all orientations of E. This result was stated originally in a slightly
different form by G. Vezzosi in arXiv:math/0004050v2 [math.AG].
