A finite past implies that there is a starting-point of time.

The finite past is best imagined with the help of a geometric straight line starting from a point and drawn to the point of the present and continuously extended with every future reached.

The question is, what does infinity mean?

Is infinity a principle of constantly adding a quantity to another?

If infinity is that, then an infinite past seems to imply a constantly moving starting-point. That is, the past is becoming more and more past, growing in some sense, which is a very strange notion that seems inconsistent. Because time has in the conventional understanding only one direction in which it proceeds.

Many points of the past (actually unlimited many) would be still potentially given and not yet realized and they would still be realized, since the past continues to spread its pastness. But the potential points of the past are not realized by the effectual present, which clearly realizes the potential future points of time.

So, according to the infinity definition, the past is not yet closed and probably not closable. Indeed, there is nothing that can make it closed and closable, since the only thing available for this purpose is what has already passed, but the past is ineffectual.

So, the given infinity definition makes an infinite past highly implausible.

I had said that time can be represented by a straight line. If the line were infinite in a direction that would be the direction to the past, this would mean that up till now an infinity of changes, has run its course. Infinite possibilities of all states and conditions have already exhausted themselves in principle. With the infinity of time already passed, infinite possibilities of events have occurred.

The question arises how these infinite possibilities could have been realized. This seems to presuppose an infinitely large potency. But where should infinite energy come from?

The only solution to the two problems mentioned seems to me to be time, understood as a circle.

In the circle of time, all points would be potential starting points, which only repeat themselves. There would be no infinite past as in the above sense.

The centre appeared to him, to be by nature, the noblest portion of the body ; from this he drew the conclusion that the heart, wrongly regarded as being in the centre of the body, must be the seat of the soul. For nearly two thousand years astronomers and physicians accepted those conclusions and went round and round, after their teacher, on the most perfect line of the circle. In passages, too many to enumerate, we detect

Even Aristotle tries to prove the perfection of the circular line by saying that, without retrogression, perpetual motion could only take place on the line of the circle, that form him alone can represent infinity.