Arrange sentences A, B, C, D between sentences $1$ and $6$ to form a logical sequence of six sentences.
1. Why are horses the same?
A. It may be old and lame, and in time it will die.
B. A particular horse ‘flows’, naturally.
C. But there is something all horses have in common.
D. You probably don’t think they are at all.
6. But the ‘form’ of the horse is eternal and immutable.