The reductive tendency that is emblematic of science has penetrated schools of meditation, and there are many, each of which advertises its particular breed as, if not being the best, at least boasting novel or specific benefits not found in other forms of meditation.
For example, there is mindfulness, which is the monitoring of thoughts. There is concentration or focus, as on an object or the breath. There is transcendental meditation, which uses the inward repetition of a phrase, or mantra, to "allow your active mind to easily settle inward, through quieter levels of thought, until you experience the most silent and peaceful level of your own awareness — pure consciousness."
Each method has its associated brain wave. Controlled focus practices involve gamma rays, seen whenever you concentrate or during “active” cognitive processing. Mindfulness practices give rise to frontal theta, a pattern commonly seen during memory tasks or reflection on mental concepts. The EEG pattern seen in transcendental meditation is frontal alpha coherence, associated with a distinct state of relaxed inner wakefulness. And we've only just broached the subject. There's Yogananda's Kriya Yoga, and the Taoist Secret of the Golden Flower, not to mention Patanjali's Sutras, Ramana Maharshi's self-inquiry, the professional athlete's "zone," and of course the advice given by Krishna to his disciple Arjuna on the battlefield, which is arguably the godfather of them all. And let's not forget the Buddhist monks, who have their own patented brand of meditation, which consists of dwelling on "loving kindness and compassion."
But what each breed of contemplation, in promoting itself as distinct and superior, fails to recognize is the overlap that unites all forms of the ancient practice. They are all yogic, and yoga means union, as in the lower self (mind) with the higher Self (unmanifest, absolute, pure Being). Whether you choose to recite a mantra, focus your awareness on an object, emotion, thought or behavior, or monitor your thoughts, you inevitably also practice the other two techniques. The practitioner of transcendental meditation is instructed while reciting his mantra to be aware of thoughts which intrude on the consciousness and in a non-judgmental and non-emotional manner bring himself back to the mantra. This is mindfulness. And the gaze is always focused on something, even when the eyes are closed and that thing is utter darkness.
So in adopting one form of meditation you glean the benefits of all forms of meditation. Your cognition improves, as does your memory. As your blood pressure falls and stress hormones levels subside, you become more relaxed and at-ease. And so we see that meditation is like going on a diet. If you do it long enough, you will get the desired result. Weight loss if you cut out bread, and a feeling of inner calm and clarity if you meditate. The trick is to stick with the practice.
Of course, the very thing we use meditation to go beyond - that is, the mind - looms as the biggest obstacle to our continued success. The personality, that psychical mind, is the wakeful enemy of all who tread the path of Self-realization. For the path leads to the inevitable extinction of thought, which is mind. Even now, I can hear it whispering the doubt whether "that can be a good path, which sets mind at defiance." This is probably why I used to say that studying spirituality was the best thing that ever happened to me, or the worst. That is, until I started meditating, and clearly see the benefits.
Because the mind, and with it the ego, must die if bliss is your aim. Years of developing the mental faculties, exploring the mind's full potential - through hallucinogenics, advanced degrees, world travels and all sorts of creative writing endeavors - has led me to the irrefutable conclusion that the more you invest in the mind, the more it can be used against you. I filled my head with all sorts of notions and philosophies and information, and wound up irritable, confused and forgetful. How did I know I was on the wrong track? Simple: I wasn't happy. The bliss stick, as I call it, went in and came out zero. Or in the minus area, even, because there was a lot of what they call negative rumination going on in my overstuffed head. The mind on overdrive is not a good thing. What you need is to power down, enter the area of no mind. Just be. That's how you contact your essence.
I speak from experience, but if you want an authority more hoary than I, Patanjali writes in his Yoga Sutras (400 AD; please read 'tis free!): "When the [the mind] takes on the form of the spiritual intelligence, by reflecting it [i.e. is without thought], then the Self [pure Being] becomes conscious of its own spiritual intelligence."
In the quiet mind the Self sees itself as in a mirror, and thus becomes not only conscious, but self-conscious. The mind reflected outward reveals the manifest world, reflected inward reveals the unmanifest source of all. Reflecting stillness, and with it gaining the bliss which is your birthright, is the purpose of the whole evolutionary process and the overriding aim of meditation, which extends far beyond physiological and psychological effects, though the thought of a higher IQ and healthier heart serves as a handy lure. In making the mind quiescent, we glimpse pure Being in that silence and stillness. And pure Being is our true nature. It is our essence. And thus the ancients say: "I am That. Thou art That. And all that there is, too."
Of course, without mind there would be no writing, and I hope you enjoyed this post. It can be a useful tool, if used to certain ends and with moderation. But between constructive endeavors, rest in the space of pure Being-Awareness-Bliss. Or BAB, for short. You can't simply read about BAB. You must DO IT.
And speaking of diets, if you're thinking about giving a food group up, cut out meat. It's one of the five commandments enjoined by Patanjali, not to mention Buddha and the Bible. (In addition not to kill we have not to lie or commit adultery or steal or drink intoxicants). Plant food is good for your midsection and for your meditation, too.