Whatever becomes accessible to us through reflection has a noteworthy
general character: that of being consciousness of something, of having something
as an object of consciousness, or to be aware of it correlatively – we are
speaking here of intentionality. This is the essential character of mental life in
the full sense of the word, and is thus simply inseparable from it. It is, for
example, inseparable from the perceiving that reflection reveals to us, that it is
of this or that; just as the process of remembering is, in itself, remembering or
recalling of this or that; just as thinking is thinking of this or that thought, fearing is of something, love is of something; and so on.
Edmund Husserl, Phenomenological Psychology, 217-218
But no matter how true it is that the mental arises as one among other real
components of the world, it still has the amazing quality – precisely that which
in phenomenology is investigated in its purity – that it relates, or lets itself be
related, intentionally [emphasis added] to everything extra-mental as well as
everything conceivable at all.