《宋书·志·卷十二》
金星、水星的积合为偶数则是早晨发生合，为奇数则为黄昏时发生合。
金、水积合，偶为晨，奇为夕。
If the cumulative conjunction of Venus and Mercury is an even number, the conjunction happens in the morning, if it's an odd number, the conjunction happens at dusk.