At a single word's puff, whose life's essence is consumed.

This profound couplet suggests that to truly grasp the essence of even a single word, one must invest their entire life's energy. It highlights the immense power and depth a word can hold. It's not just about hearing or reading; it's about deeply contemplating, scrutinizing, and allowing that word to resonate within your very being. To truly 'test' or 'measure' a word's significance, it requires a part of your 'life's vapor' – your vital energy, your understanding, your soul. It implies that true wisdom and understanding come from a deep, almost spiritual engagement with language, where each word is a universe in itself, demanding our full, dedicated attention.