Early studies of sleep and dreaming were crucially dependent on waking subjects up during sleep to find out whether they are dreaming or not. Using that strategy, it was found that when the eyes are rapidly moving (REM sleep) people are usually dreaming; when the eyes are not moving, there may be some mentation, but little in the way of visually rich dreams.

Being engaged in some way for the good of the community, whatever that community, is a factor in a meaningful life. We long to belong, and belonging and caring anchors our sense of place in the universe.

It is important to understand that while oxytocin may be the hub of the evolution of the social brain in mammals, it is part of a very complex system. Part of what it does is act in opposition to stress hormones, and in that sense release of oxytocin feels good - as stress hormones and anxiety do not feel good.

Studies of decision-making in the monkey, where activity of single neurons in parietal cortex is recorded, you can see a lot about the time-accuracy trade-off in the monkey's decision, and you can see from the neuron's activity at what point in his accumulation of evidence he makes his decision to make a particular movement.

Remember, in the heyday of vitalism, people said that when all the data are in about cells and how they work, we will still know nothing about the life force - about the basic difference between being alive and not being alive.

When that theory is isolated from known facts, it is likely not to be productive.

When philosophers try to understand consciousness, much of what they claim is not conceptual analysis at all, though it may be shopped under that description.