This One day a monk asked Tōzan Ryokai:
“How does one evade the elements in times of severe cold and severe heat?”
“Why, all you need do is go to a place where there is no cold or heat.”
“Where can I find such a place?”
“In times of cold, let the cold be the death of your ego; and in times of heat, let the heat be the death of your ego. That is the place of no cold or heat.”
The place where cold or hot exists in no specific entity, a place where there is no absolute measure of cold or hot, is the place of mukanjyo.
Tōfukuji Zen Training Master Keitō Fukushima points us to the meaning behind ‘let the hot and cold be the death of your ego’. “When it’s cold, don’t get fixated in the thought “It’s cold!”; embrace the cold*. And when it’s hot don’t get fixated in the thought “It’s hot!”; embrace the heat*. When you experience hot and cold weather, realise it’s only subjective experience, it’s neither a part of you or the outer world. There is no absolute measure of hot or cold. This is the place of 'mukanjyo' no hot or cold.”
*The implication is you use your subjective experience of hot or cold as a stimulus to realise it's only your ego that's having the experience. Therefore, extinguish your ego. By throwing away your ego, you throw away any measure of hot and cold and you simply 'are' in the midst of the elements. The discomfort you experience from the fixation on your subjective experience of hot or cold dies.