Way Out Stations

On Page Seventy nine, Sayadaw finishes up the kasinas with the 'space kasina' which one can visualize through a hole, looking at the sky and concentrate on space.

He continues with "Once you have attained the four jhanas with each of the ten kasinas, you can proceed to develop the four immaterial jhanas which are:

1. The Base of Boundless Space
2. The Base of Boundless Consciousness
3. The Base of Nothingness
4. The Base of Neither perception-nor-non-perception

And he notes that these bases can be devloped with all of the kasinas except the space kasina.

The third and fourth jhanas above are exactly what the Buddha's teachers Alara Kalama and Uddaka Ramaputta had attained to.   High practice, but stations on the way nonetheless.