心如深海自然冷心如太阳自然暖
[xīn rú shēn hăi zì rán lĕng xīn rú tài yáng zì rán nuăn]
It metaphorically means one's heart is like a deep sea which feels naturally cold, and like the sun that feels naturally warm. It describes contrasting aspects of one's personality - cold and calm sometimes while being fiery and loving other times.