They are attributes grounded on facts, that is, on states of consciousness, but on states which are peculiar, unresolvable, and inexplicable.
"A System Of Logic, Ratiocinative And Inductive (Vol. 1 of 2)"
John Stuart Mill
And in the case of unresolvable or "elementary" substance, the molecule and the atom are not necessarily the same.
"Creation and Its Records"
B.H. Baden-Powell
The problems seem unresolvable.
"How and When to Be Your Own Doctor"
Dr. Isabelle A. Moser with Steve Solomon