The next part of the lessons here is another principle, which is valid everywhere. The principle of polarity. As you might think of "dualism", you better forgot about it instantly. I will now explain, what difference we have here.
The principle of polarity is as follows:
"The Principle of Polarity embodies the idea that everything is dual, everything has two poles, and everything has its opposite. All manifested things have two sides, two aspects, or two poles. Everything "is" and "isn't" at the same time, all truths are but half truths and every truth is half false, there are two sides to everything, opposites are identical in nature, yet different in degree, extremes meet, and all paradoxes may be reconciled." (Yes, it's quote from wikipedia article about kybalion)
If we now transfer this to natural circumstances, let's take the evolution. As you know, we "humans" just didn't came out of nowhere. We are a naturally, evolutionary process. First we were little molecules, then stars, then first living forms, then apes, then humans. So, there is no "jumping" in polarity. That's where we also meet another principle, which is very connected with the principle of polarity: Vibration. Everything has a vibration and every vibration therefore has a pole. And this effects in ENDLESS poles. That's why for example, a desert doesn't starts at exactly one point, but more likely starts evolutionary. It gets hotter, the bottom is changing, the plants, etc. An evolutionary process.
So, there are days that will be "positive" for you and there will be days that will be "negative" for you. If you know have cause and effect in your backmind, you can actually cause positive days. And how? That's your decision. Like I said, everyone has another experience of positive and negative. Some people think that positive days are more likely days where you can fight with others and punch in their faces, while others think positive days are friendly, peacefully days without hesitate and nervousity. And some think negative days are days where everything was too quite and no activity was within. So, by more you learn to understand cause and effect, you can also cause your positive days. But remember, even if you're able to handle your causality and your doings, you won't have positive days forever. YOU'RE GOING TO have a bad day some day.
so, let's say for example a positive pole of a day is, that your friends accept you as you are, that you get good marks in school, have a peacefully life. And the negative pole of a day would be the direct opposite of course.
Now you're able to control your causality and you always do stuff now on your daily life now, that causes the positive pole of your day. This worked for a while now, let's say for 1 or 2 years. Now immediately the day was horribly bad. (Remember, the better and better your previous days were, the worse the negative pole will be once you experience it. But this is a subjective aspect! So you may experience it as the worst day in your life, while others think that this is routine in their life and think that they had worse days!) You now turn into a depressive person and start to suggest you more negative stuff like: "What happens if the next day my friends are still that kind of assholes to me?", "What if I'm getting nervous again?" All that stuff can cause for very bad experiences and will only bring you deeper in shitty stuff.
So, if you experienced a bad day, don't worry! Just make out of your bad day a good day! Try to "enjoy" that bad day. Simply laugh about the bad stuff that happened on your bad day and forget about it!
The other stuff
If you now use that principle and use some analogies somewhere else, you're going to discover a lot more and will see the reciprocation of polarity in all aspects of nature. Shall it be physical, astral or mental nature.