While the general aviation community is for the most part unaware of the
vital role played by Lift Demons, the FAA has for a long time taken them
into consideration when formulating Federal Aviation Regulations. In fact,
understanding the needs and wants of Lift Demons greatly helps in
understanding many of the rules that the FAA has introduced over the years
(which otherwise make little sense to the average pilot).

For example as it turns out there are two types of Lift Demons. Bird Demons
and Bat Demons. Bat Demons are blind because they evolved along side bats in
caves, they also have sticky feet which help them to grip onto the more
slippery wings of bats. Now, when man first took to the skies, it was on the
wings of bird demons (Seagull demons to be exact in Kittyhawk). However,
before long some bright sparks decided that unlike birds man would fly his
airplanes inside clouds (not something that birds usually do - I mean have
you ever seen a bird inside a cloud ?). Straight away there was a problem.
Bird Demons need to be able to see where they are going and when they can't
see they get scared and quickly jump off the plane - causing unfortunate
accidents. Should you every fly into a cloud by mistake - quickly start a
180 degree turn to get out of it before the Lift Demons panic. However,
before long a solution was found, Bat Demons, being blind didn't panic
inside a cloud, they didn't need to see in order to keep the lift working.
As a bonus, their sticky feet helped them grip wet slippery wings which is
common when inside a cloud. However, there are not very many Bat Demons (at
least compared to Bird Demons) so you need to make sure some Bat Demons are
waiting for your plane at the runway before you take off if you are planning
on flying into a cloud. The FAA realized this and created the Air Traffic
Control system to facilitate the timely coordination of Bat Demons and
planes. And that is why FAR 91.173 exists

Sec. 91.173

ATC clearance and flight plan required.

No person may operate an aircraft in controlled airspace under IFR unless
that person has--
(a) Filed an IFR flight plan; and
(b) Received an appropriate ATC clearance.

You see, when you file an IFR flight plan the flight service station
computer sends a message to the nearest colony of Bat Demons telling them
where and when they will be needed. Actually, the demons we all know that
live inside computers can communicate directly with their demon brothers -
so the Bat demons don't need their own computers. The Bat Demons don't
always turn up on time, which is why you can't actually take-off until ATC
sees the Bat Demons arrive and issue your IFR release. Sometimes, when the
weather is really bad and lots of planes want to fly in the clouds, there
are not enough Bat Demons to go around and you have to wait a long time on
the ground for some to arrive.

It all starts to make sense when you think about it. Bird Demons don't even
like getting close to clouds. That is why you always have to ask ATC for
Special VFR, this gives them a chance to call up at least a few Bat Demons,
to keep all the other Demons calm as you fly close too the (but not in) the
clouds. Class bravo airspace has so many big jets flying with lots of Bat
Demons that there is always a few extra around which lets you get closer to
the clouds as well.