You have two apples … take away one, and there's one remaining. That's subtraction, right? Now what if you take away the last one? There's a void of apples remaining—which is bad if you're hungry. But if you have a headache and it's taken away, you're left with a void of headaches, which is good.
When you look back at what you're looking out from, you may glimpse (intuit, sense, feel, etc.) a void … a void of things, which scares you. But all things are ultimately headaches, if for no other reason than their transience. The path to absolute truth or self-realization proceeds by a process of elimination. Unlike objective science, mind science begins with an assumption (to state it facetiously) that, "I'm all that and a bag of chips." As we go within, our assumption progresses to, "well, I'm all that, anyway (excluding the bag of chips)" then to, "maybe I'm not all that after all," and so on. More specifically, we start with a set of beliefs like: "I'm a body with a great, if under appreciated, personality and limitless abilities."
We can tentatively conclude we're not the observable body … the fingers and toes, and so on. But we have to concede that our consciousness may depend on body parts that we don't observe (i.e., the brain and its supporting equipment). We can come to see that we're not our thoughts, not our feelings, not the mental processes such as decision-making … which are all observable objects or operations. But we're still left with the conviction of being a separate being, an aware something; still stuck with a split between what we are and what we know. Are you satisfied to live and die that way?
Looking back on your path to self-realization you may see certain milestones you couldn't see at the time. I'd describe those markers in terms of three stages and three gates of becoming.
Gate #1 is an intuitive recognition: "Aha … the answers are within." This could be labeled the disciples' gate. Of the hundreds and hundreds of people whom Jesus or Gautama talked to, maybe one in a hundred or thousand picked up on their message. Jesus apparently had 72 disciples, Gautama 80.
Gate #2 is the intuitive realization: "I'm still connected to my source." It could be called the apostles' gate. Maybe one in 6 or 7 of the disciples can act in the Zen sense. Gautama had 11 bhikkhus, Jesus 12 apostles.When we reach the determination that we can no longer rely on second-hand beliefs, "I won't run away or procrastinate any longer … I have to see/know for myself—now—what I am," we've passed through Gate #3. I'd call it the millionaires' gate. Maybe 1 in a million seekers persist to that point.
In the first stage of becoming, we identify with a personality: "I'm a person who…." Personality is a mask that, as the years add on, reflects more and more clearly our character traits and dispositions. In the second stage, we progress to where we identify with the individuality sense behind the mask: "I am a separate awareness." At some point during this stage our search becomes an egoless vector aimed at the truth. The third and final stage is that of Being, of self-realization. Our illusory self-definitions have vanished.
To recognize Truth or Self, we need to look for it—first noticing what we're looking at, and then determining if it's what we're looking for. If not, we move on (subtraction). Triangulation over a set of opposites is the process by which we back into Truth. The path to Truth is a voyage of disillusionment. Living life and pursuing Truth are not mutually exclusive endeavors. We live a life aimed at finding the truth about that life.