Why study Samkhya? Well, I started out by reading the Yoga Sutra. Chapter 1, verse 3 states: "(When the fluctuations of the mind have been restrained (nirodhah)), Then the seer stands in his own nature."
The first thought that came to mind when I read this verse was, "What the hell is 'seer'?" The Tattva-vaisaradi, a commentary on the Yoga Sutra, explains this verse thus, "...the objects of the purusa (self) are discriminative knowledge and the experience of the objective world. These two no longer exist in the state of inhibition (nirodhah)."
Hmm... very nice, I think to myself. So the seer is the purusa that is free from discriminative knowledge and experience of the objective world as a result of restraining the fluctuations of the mind...
Okay. But all this is useful only if we already know what "purusa" means. Yeah, the guy who translates the commentary translates purusa as "self", but "self" could mean a million possible things in philosophy. So unless we know what "purusa/self" refers to, we really won't know what this simple verse means.
Clearly, a little more background study is needed if my reading of the Yoga Sutra is going to be fruitful. So I decided to turn my attention to Samkhya. Samkhya provides the metaphysical and psychological foundations of Yoga. It is in Samkhya that the concepts of Purusa (self/spirit) and Prakriti (Nature) are explained and articulated. We can also think about it this way: If Yoga can be seen as a vehicle for attaining self-realization, then Samkhya is both the owner's manual and a road map: It explains the inner workings of the vehicle, and also maps out the terrain to be covered in getting to self-realization. Crude analogy, I know, but this is the closest one I can find :-)
What, then, is the difference between purusa and prakriti? The Samkhya-karika describes prakriti as being "with the three gunas [sattva, rajas, tamas]", "objective," "common", insentient" and "productive." (verse 11) By contrast, purusa is the reverse of all this. As such, purusa is '"witness", and has "isolation", "neutrality," and is the "seer" and "inactive." (verse 19)
Since only prakriti has the three gunas, and the three gunas are responsible for all activity and motion in the world (both mental and physical), what this means is that only prakriti is capable of moving and producing things in the world, since only prakriti has the three gunas. As such, minds and bodies, being imbued with the three gunas, are "objective" things in an "objective" world. By contrast, Purusa (spirit or self), being the "subjective" observer, is the inactive seer that is isolated from the objective worlds of the mental and physical.
Thus, there is this interesting distinction in Samkhya and Yoga between the subjective spirit (purusa) and the objective body and mind (prakriti). At the risk of oversimplifying things, all of this suggests that both Yoga and Samkhya privilege the subjective over the objective. Well, this is not, strictly speaking, true: Verse 52 in the Samkhya-karika states that 'Without the "subjective", there would be no "objective", and without the "objective" there would be no "subjective."' So perhaps it is more accurate to describe the relationship between the subjective and the objective as being a sort of interdependent relationship; one cannot exist without the other.
Nevertheless, the subjective spirit is privileged over the objective mind and body in the sense that bondage always occurs as a result of prakriti and the three gunas. Bondage occurs because the bonded self (jiva) is unaware of its true nature and is deluded into the belief that it thinks, feels and acts in an "objective" world. Jiva only attains freedom (kaivalya) when the fluctuations of mind are stilled (nirodha), and it is able, for the first time, to clearly see its true self (purusa), which is always free and isolated from the objective realm of thought and movement. This attainment of freedom through nirodha is, of course, the goal of yoga.
One common theme that runs through the above exposition is the privileging of the subjective over the objective. On a rather more mundane level, this explains why no amount of objective, detached study of yoga--whether we are talking about study of its health or psychological effects, or about a detached, "scholarly" study of yogic texts without practice--can yield any truly fruitful insight as to the true nature of yoga if such study is divorced from first-hand, subjective experience. This brings to mind David Williams' famous words, "Before you practice, the theory is useless. After you practice, the theory is obvious." In a different context, I also once read somewhere that Guruji would never grant an interview to anybody who was not a practitioner of Ashtanga. I can't pretend to know what was in Guruji's mind when he made this decision, but it seems reasonable to think that he decided not to grant such interviews because any "objective" attempt to understand yoga that is divorced from subjective practice can only, at best, present to the listener a distorted view of the true nature of yoga.
On a broader level, this privileging of the subjective over the objective also runs counter to an important keystone of contemporary western thinking and practice: I think it is no exaggeration to say that much of western science and philosophy emphasizes the objective over the subjective. Controlled scientific studies are prized for being "objective". The same emphasis on objectivity--or, at the very least, purported objectivity--also runs through much of western journalism. The journalist prides herself on being a detached observer of things from many angles. Such an approach is not without its merits, but I can't help feeling that such "objectivity" often comes at the price of a more genuine understanding of the subject matter. This is especially true if the subject matter concerns some very particular human experiences. It is even more true when the subject matter concerns a spiritual or religious movement (for more details, see my recent post on the 2000 New Yorker article about Ashtanga Yoga). By not putting oneself into the position of the spiritual seeker and fully feeling the entire weight of the seeker's spiritual aspirations in all its intensity, the objective reporter tends to characterize the seeker as either some kind of flaky hippie/new-age type or some kind of misguidedly-devoted fanatic, and essentially misses the point of what is really going on.
Well, not sure what else to say here. I'm quite blogged out now, and can't even think of a nice way to wrap up this post. So I guess I'll just leave you with these all-over-the-place thoughts :-)