Suppose I have a book, you ask me what I’m looking at, and I say, “It has white, rectangular pages made of pressed wood pulp. On the pages are straight, horizontal rows of black letters”.
Well, that’s the objective nature of the book. What does this tell you about what the book is about? Nothing, of course! :) It could be a steamy romance, a description of how to achieve world peace, or an explanation of quantum mechanics.
The subjective nature of the book is the realm of thoughts, ideas, intentions. If I can read the book, if I know how to read, and it’s written in a language I can understand, it creates thoughts and ideas in my mind.
The book needs objective reality to exist. If every copy of the book was destroyed and everyone who had read the book died, that knowledge would be lost.
But the subjective nature of the book is also independent of objective reality. It’s the same book, the same story, if displayed with electrons or carved on stone tablets. A story could even be passed on through generations as an oral tradition without ever being written down.
People might say subjective reality doesn’t really exist. Well, suppose I break a law and I’m thrown in jail. Where is this “law”? It exists in the minds of people. We decided to have a “legislature” that would think up “laws” and then other people will decide whether or not to throw me in jail depending on what those laws say. For something that’s not “really real”, it makes a pretty big difference to me!
Both objective reality and subjective reality are real. If I jump off a cliff, the objective nature of gravity matters to me a lot. Yet most of the things I create in my life start with my thoughts: whether it be making money, or being in a relationship, or giving useful advice.
I may be somewhat constrained by objective reality, perhaps I want to be with someone and they live far away... yet the difference I can create in outcomes comes primarily from my subjective creation.
Many people give their power away, becoming less effective than they could be, when they say only objective reality is real. For example, they might say they can’t make money, or that we can’t bring an end to war, as if that was some objective physical constraint of the universe.
Because we usually think in terms of objective reality, it can be a useful practice to look at the world from the perspective that subjective reality is primary. For example, what if the world around us that we see was actually a dream, or the inside of a very advanced video game? After all, if we were in a dream or simulation, we might still think that what we were seeing was objective reality.
This may be going too far for some people... but to go off the deep end — I mean, to explore further — check out Steve Pavlina’s Subjective Reality Q&A :D