7. " he it is who has sent down to you the book; in it are
decisive verses which are the basis of the book, while others are allegorical.
but as for those in whose hearts there is perversity,
they follow the part of it which is allegorical,
seeking (to cause) dissension by seeking it (their own) interpretation,
while none knows its (hidden) interpretation except allah
and those firmly rooted in knowledge. they say: ` we believe in it,
the whole (of it) is from our lord;' and none minds
save the possessors of intellect."

commentary:

the decisive & the allegorical verses in the qur'an.
in former verses, the statement was upon the revelation of the
qur'an as one of the clear evidences and proofs of the prophethood of
the prophet of islam (p.b.u.h.). now, in this holy verse, one of the
specialities of the qur'an is pointed out. this quality is the manner of
expressing statements that is applied in this grand heavenly book. at
first, it says:

" he it is who has sent down to you the book; in it are decisive verses which
are the basis of the book, while others are allegorical. ..."

these allegorical verses, that in the first glance seem complicated
because of high level of the subject or of other factors in them, are
criterions to try individuals in order to separate truthful scholars from
stubborn seditious persons. so, next to that, it says:

"... but as for those in whose hearts there is perversity,
they follow the part of it which is allegorical,
seeking (to cause) dissension by seeking it (their own) interpretation,
while none knows its (hidden) interpretation except allah
and those firmly rooted in knowledge. ..."

then, it points to those who, under the light of their correct
understanding the meaning of both decisive and allegorical verses,
declare:

"... they say: `we believe in it: the whole (of it) is from our lord;'..."

yes! verily :

"... and none minds save the possessors of intellects."

through the above mentioned verse, it is recognized that the
verses of the qur'an are divided into two groups. a part of the verses
have such a clear concept that there is no place for denial, justification
or misuse in them. these verses are called `decisive verses'. but there
are other verses that, because of high level of subject or discussing
about things which are out of our reach, like: the unseen world, the
world of resurrection, and the attributes of allah, are such that their
hidden meanings and the secrets and the depth of their reality need a
particular scientific ability to be rendered. these verses are called
`allegorical verses'.

some perversive persones try to abuse these verses by
commenting on them untruly in order to make mischief among people
and deviate them from the right path. but allah and those firmly
rooted in knowledge know the secrets of these verses and explain them
for people.

of course, those who are in the first line, from the point of
knowledge,
(like the prophet and immaculate imams), know the whole
secrets while others may understand from them as much as the amount
of their own knowledge. hence, it is this very fact that sends people,
even the learned scientists, after the divine teachers to catch the
mysteries of the qur'an.