Descartes makes a complicated argument.
That phrase is only meant to sum up his point.
I don't know what this means. It sounds like nonsense to me. Awareness requires thinking.
is the study of what exists.
As opposed to:
, which is the study of what can be known.
, which is the study of what we experience.
Before you can talk about 'what exists', you have to first define what 'knowledge' is, and how you have access to knowledge.
Doesn't matter, if you are questioning what it is, you are thinking.
No, all you can be sure of is that thinking exists, it might not have a cause. Thinking might be self-caused.
I'd say that is debatable. You're using 'no thing' as a noun, which is useful, but its a function of language. 'Nothing' is just a negation of whatever thing you are talking about. Nothing is not a thing, like an apple is a thing. Nothing is a lack of something.
The real issue here is causation. In our everyday life, we experience a world of cause and effect. The old problem of course is, if everything has a cause, you get an infinite regress of events. That doesn't solve the problem however, that is the problem. Because the next question is, what caused the world be like it is?
Some people address this by saying that there was a 'first cause' which started the ball rolling. But if a first cause exists, then that means that not everything needs a cause, so you really don't need a first cause. There could be a dozen, or a million things that aren't caused. You could have random events.
Causation is problematic... and that's not even getting into the 'problem of induction
If something is eternal, then progress is meaningless. In order to have progress, you have to have a significant difference between point A and point B. But if the universe is eternal... any difference between any points becomes insignificant.
I don't have much use for supernatural explanations, they don't really explain anything, and they tend to just add further complications.
I'd say the voyage is the only important thing.