【事出有因】〖shì ch yu yn〗[thing has its cause; by no means accidental; not entirely devoid of truth; The cause is not far to seek; Where there is smoke , there is fire]

事捷功倍诗典成，

出其不意中外凝。

有备无患灭私制，

因时制宜向大同。

事情的发生是有原因的。Thing of happen is has reason of.同：理所当然、顺理成章。反：平白无故、莫名其妙。歇：老太婆改嫁。谜：原作、张飞审瓜。