Having a lucid dream requires, by definition, knowing that you are
dreaming. If there were no differences between dreaming and waking
life, there would be no way to know that you were experiencing one
state and not the other. Fortunately, there are characteristic
differences between the two states that allow you to know whether
or not you are dreaming. In other words, there are features that
make dreams “dreamlike.” Learning to recognize these distinctive
features, typically termed “dreamsigns,” is one of the most basic
and powerful methods of inducing lucid dreams.
Examples of dreamsigns include: miraculous flight, changing
writing, malfunctioning devices, and meeting deceased people. By
studying your dreams you can become familiar with your own
personal dreamsigns and set your mind to recognize them and become
lucid in future dreams.
The cultivation of dreamsign awareness as a method for learning
lucid dreaming is described in full detail in
Exploring the World of Lucid Dreaming (EWLD),
and
A Course in Lucid Dreaming. The Course also
provides exercises for noticing dreamsigns while you are awake, so
that the skill carries over into your dreams. This exercise also
applies to lucid dream induction devices, which give sensory
cues—special, artificially-produced dreamsigns—while you are
dreaming. To succeed at recognizing these cues in dreams, you need
to practice looking for them and recognizing them while you are
awake.
Most dreams you recall will contain at least one, but more likely
several dreamsigns. Until you have developed at least a moderate
degree of lucidity, you will almost never recognize these dream
oddities for what they are, and this leads to a pitfall which can
block progress until it is understood and corrected: the mistake
(common among novice lucid dreamers) is to focus on how uncritical
their minds are during dreaming, using each missed dreamsign as
another example proving that they “never recognize dreamsigns”.
This is a mistake! If you do that, you use missed dreamsigns to
learn that you're too unreflective, stupid, or whatever to become
lucid. This isn't what you want to learn, is it?
What you want to learn is how to recognize when you're dreaming by
getting to know your dreamsigns. Thus you should make sure that
you reflect on which parts of your dream could have told you that
you were dreaming, and resolve that the next time something like
that dreamsign reoccurs, you remember that you are
dreaming! So, if you wake from a dream in which you fail to notice
that the friend you were talking to has been dead for years, you
firmly resolve that if you ever see that person again you will
realize that you're dreaming. Furthermore, resolve that you will
see your friend again, and that the next time you do, you will
become lucid.
Missed dreamsigns are stepping stones across the river of
forgetfulness to lucidity. But only if you use them as such; only
if you decide with complete conviction that you won't get fooled
again. Of course, you will. To err is human, but why not learn to
err less and less?