You reach the second gate of dreaming when you wake up from a dream into another dream. You can have as many dreams as you want or as many as you are capable of, but you must exercise adequate control and not wake up in the world we know.
I'm not saying that you should never wake up in this world. But I have to tell you that that is an alternative. The sorcerers of antiquity used to do that, never wake up in the world we know. It certainly can be done, but I don't recommend it. What I want is for you to wake up naturally when you are through with dreaming, but while you are dreaming, I want you to dream that you wake up in another dream.
This control is no different from the control we have over any situation in our daily lives.
There's one problem with the second gate. It's a problem that can be serious, depending on one's bent of character. If our tendency is to indulge in clinging to things or situations, we are in for a sock in the jaw.
Imagine yourself going from dream to dream, watching everything, examining every detail. It's very easy to realize that one may sink to mortal depths. Especially if one is given to indulging.
Wouldn't the body or the brain naturally put a stop to it? Yes, if it's a natural sleeping situation, meaning normal. But this is not a normal situation. This is dreaming. A dreamer on crossing the first gate has already reached the energy body. So what is really going through the second gate, hopping from dream to dream, is the energy body.
The implication is that on crossing the second gate you must intend a greater and more sober control over your dreaming attention: the only safety valve for dreamers.
You will find out for yourself that the true goal of dreaming is to perfect the energy body. A perfect energy body, among other things of course, has such a control over the dreaming attention that it makes it stop when needed. This is the safety valve dreamers have. No matter how indulging they might be, at a given time, their dreaming attention must make them surface.
Crossing the second gate is a very serious affair; it requires a most disciplined effort.
I told you that one has to wake up in another dream, but what I meant is that one has to change dreams in an orderly and precise manner.

There are two ways of properly crossing the second gate of dreaming. One is to wake up in another dream, that is to say, to dream that one is having a dream and then dream that one wakes up from it. The alternative is to use the items of a dream to trigger another dream; that is, zoom from a definite item accessible to your immediate dreaming attention to another one, not quite accessible. Or gaze at any item of a dream, maintaining the gaze until the item changes shape and, by changing shape, pulls you into another dream.