What does the Book of Changes mean?

The explanation downstairs is too complicated. In the Book of Changes, 12345 is a birth number, 6789 is a positive number and even number is a negative number. Yang number is vigorous and upward, and 9 is the largest odd number among positive numbers. The number of yin is restrained from sinking, and 6 is the smallest even number in the number, belonging to the old yin, so 9 represents yang and 6 represents yin. Similarly, you will know why we often say "seven ups and eight downs", because 7 is a positive number, so 8 is a negative number. Then, count a hexagram from bottom to top, the first is the first, and the second is the first. Three, four, five and six, not one, two, three, four, five and six, because at first, time is more important.