《管子·枢言》
机密，就是不可说出口，不可形于色，就象龙、蛇一天五变而无人察觉一样，才叫作保持机密。所以，先王总是不肯惊人地把一说成超过二，先王也不肯独自包办事业或独自居功。
周者不出于口，不见于色，一龙一蛇，一日五化之谓周，故先王不以一过二，先王不独举，不擅功。
Secrecy means that it cannot be said aloud or shown in one's expression;  just like how dragons and snakes can change five times a day without anyone noticing, that is what it means to maintain secrecy. Therefore, the ancient sages always refrained from making one out to be more than two in a surprising way, and they also refrained from taking sole responsibility for an undertaking or claiming sole credit.