Final answer:
The narrow road to the deep north is a metaphorical and sometimes literal path representing a difficult and challenging journey that demands resilience and courage, often symbolizing personal struggles or goals.
Step-by-step explanation:
The narrow road to the deep north possesses a certain symbolic meaning which can be extracted from the different contexts in which it appears across literature and historical references. Described often as fatiguing and challenging, it typically symbolizes a difficult journey or a pathway that requires perseverance and determination. This metaphorical path can also be a representation of a person's life journey, with its various challenges and obstacles. In some instances, the narrow road can be physically daunting and dangerous, as it may lead through treacherous terrains, like narrow mountain passes, which armies would find difficult to navigate. Other times, it's a reference to a solitary and untraveled route which, despite its straightness and clear direction, is eerie due to its lack of human presence, illustrated by descriptions such as a lack of bordering fields, dwellings, or even the sound of a barking dog to suggest human habitation.