At the beginning you can see only the line.
But soon after, you discover
the shape of the circle.
The change comes with the notion of cycle
which isn’t only a circle.
Because the cycle isn’t closed.
It’s always open
in the sense that it’s connected
with another cycle.
The end of the first can be
the beginning of the second.
To go further and beyond the cycle,
you need the more complex notion
With this concept
you can understand
even more deeply
not only Upanishads
but also a part of the core
of Hinduism, Jainism and Buddhism.
Then it will be possible for you
to discover why there is a need
to accumulate good karma
to achieve a better cycle.