1. "The entire characteristics of a species and the generic characteristics of a species lie in the nature of life activities, and the generic characteristics of human beings are precisely free and conscious activities." - "The Complete Works of Marx and Engels" No. 42 Volume, page 96

2. "Because their needs, which are their nature, and the way they seek to satisfy them, connect them (sexual relations, exchange, division of labor), they must interrelationship occurs.

"("The Complete Works of Marx and Engels", Volume 3, page 514)