Sentence:  The correlation between warmth and cold is an internal one where the existence of one depends on and is defined by the other. Hence, the yin-yang <WSD>binary</WSD> as a correlative <WSD>binary</WSD> of light-shade or warmth-cold [...] 
Meaning of the word marked with <WSD> tags:  A thing which can have only (one or the other of) two values.