The fundamental way to insure this is to be cautious and strict in recruiting. Nor is it permissible for everyone to know everyone and everything else. Each person should know only what relates to his work. This rule is a fundamental point in the abc's of urban guerrilla security. The battle that we are waging against the enemy is arduous and difficult because it is a class struggle.
Every class struggle is a battle of life or death when the classes are antagonistic.
The enemy wants to annihilate us and fights relentlessly to find us and destroy us, so that our great weapon consists in hiding from him and attacking him by surprise. The danger to the urban guerrilla is that he may reveal himself through imprudence or allow himself to be discovered through lack of class vigilance. It is inadmissible for the urban guerrilla to give out his own or any other clandestine address to the enemy or to talk too much. Annotations in the margins of newspapers, lost documents, calling cards, letters or notes, all these are clues that the police never underestimate. The points of contact should not be written down but simply committed to memory.