In Book Four of the Masnavi, Rumi explores the concept of true maturity through the Prophet's justification for appointing a young Hudhayli man as a military commander over older, more experienced veterans. Rumi argues that true seniority and leadership capability are derived from spiritual intellect (عقل) and inner purity rather than chronological age or physical signs like white hair. He famously declares that 'an elder is an elder in intellect, O son, not by the whiteness of hair in beard and head.' This highlights the Sufi perspective that a spiritually enlightened youth, free from ego and worldly delusions, is vastly superior to an old man who remains spiritually immature or hardened.