Final answer:
The blank in the phrase should be filled with 'hand', reflecting the personal, direct experience of learning by burning one's hand against the fire.
Step-by-step explanation:
The correct answer to the question "....the disappointment comes on one who knoweth nought till he burn his ___ against the hot fire." is A) Hand. This phrase metaphorically suggests that an individual will not truly understand or feel disappointment until they experience it firsthand, which in this context means burning the hand against hot fire. This idea can be connected to various experiences or contexts where direct experience is necessary for genuine understanding. The metaphor of burning one’s hand on the fire is used to represent receiving a painful yet enlightening lesson. The passages provided, drawing from texts that involve extreme cold and fire, underscore the visceral, immediate understanding that comes from direct physical experience, be it touching a hot object or enduring the bitter cold. These examples emphasize the concept that certain knowledge or understanding can only be acquired through direct, often painful, personal experience.