essence and fringe; root and branch; means and end
Used in philosophical or analytical contexts to contrast the fundamental and the peripheral, or the essential and the incidental. Often appears in the set phrase 本末を転倒する (to put the cart before the horse).
Don't confuse the means with the end.
彼の議論は本末をわきまえていない。
His argument doesn't distinguish between the essential and the incidental.
putting the cart before the horse; mistaking the means for the end; getting priorities backwards
topical-annalistic style
Compound of 本 (root, origin) and 末 (tip, end). The pairing of these two characters to express the relationship between the fundamental and the peripheral is a classical Chinese-derived concept.