The 4 Jhanas – this article is part of the TiltedCandle series on the 7 sets
The Buddha told a merchant that every man has four spiritual bodies. When the merchant asked him if every man has them at the same time, the Buddha told him no. We do not have them at the same time. The bodies are like milk, cream, butter, and cheese. We churn milk until it is cream, then butter, then cheese. We do not have milk and cream at the same time.
The process of developing a spiritual body is therefore similar to a phase change, ice melting to water, water boiling to steam. Also in my experience, there is a kind of latency effect. You pour energy and effort into the work, and there are results. But depending on how you observe, there may seem to be a plateauing effect.
When you heat water to boiling, there is a direct linear relationship between the energy you apply to the water and the rise in degrees of the water temperature over time. When the water comes to boiling, it does not get any hotter. Instead, that energy now has a direct linear relationship to the mass of the liquid water being liberated into steam.
The bodies the Budda was describing, which are organic and naturally-occuring phase changes, like the conversion of milk into cheese, are Jhanas. There is a little bit of slack and difference in the description of the Jhanas. It seems to me these differences are largely due to whether the source is describing the state the body is in (liquid or steam) or the process of conversion between them (boiling). More