AC 2515 & 2516 - thoughts and thinking from the rational

AC 2515
There are thoughts from perception;
thoughts from conscience;
and thoughts from no conscience.

Thoughts from perception exist only with the celestial,
that is, with those who are in love to the Lord;
such thought is the most internal that exists with a person;
and it exists with the celestial angels in heaven,
for it is perception from the Lord
by which and from which their thought exists;
and to think contrary to perception is impossible.

Thoughts from conscience are lower,
and exist with the spiritual, that is,
with those who are in the good of charity and faith 

as to life and as to doctrine.
Moreover with these persons to think contrary to conscience is impossible;
for this would be to think against the good and truth
which are dictated to them from the Lord through conscience.

But thoughts from no conscience exist with those
who do not suffer themselves to be inwardly directed 
by what is good and true,
but only by what is evil and false;
that is, not by the Lord, but by themselves.
Such persons believe that they inwardly think
 just as do those who think from conscience and perception,
for the reason that they do not know what conscience is, still less perception;
but the difference is as great as is that between hell and heaven.
They who think without conscience
think from any cupidities and fantasies whatever; thus from hell;
and when it seems otherwise,
it is from external decorum for the sake of reputation.
But they who think from conscience
think from the affections of good and truth; thus from heaven.
But as regards the Lord's thought,
it transcended all human understanding,
for it was immediately from the Divine.

AC 2516 [2-3]
The reason why there is no doctrine of faith from the rational,
is that the rational is in appearances of good and truth,
which appearances are not in themselves truths.
Moreover the rational has under it
fallacies which are from external sensuous things
confirmed by memory-knowledges,
which induce obscurity in these appearances of truth.
The rational for the most part is merely human,
as also is evident from its birth;
and this is why nothing doctrinal of faith can begin from it,
and still less be constructed from it;
but must be from the Lord's Divine Itself and Divine Human.
This is its origin, and indeed so entirely 
that the Lord is doctrine itself;
on which account also in the Word He is called
the Word, the Truth, the Light, the Way, the Door;
and (what is an arcanum)
all doctrine is from the Divine good and the Divine truth,
and has in itself the heavenly marriage.
Doctrine that has not this in it is not the genuine doctrine of faith.
So it is that in all the particulars of the Word (the source of doctrine)
there is an image of a marriage.

In the literal or external sense of the Word
the doctrine of faith does indeed appear
as if it possessed much from the rational,
and even from the natural; 
but this is because the Word is for mankind,
and has been in this manner accommodated to him;
but still in itself it is spiritual from a celestial origin,
that is, from Divine truth conjoined with Divine good.