In the Tenth Veil of Kashf al-Mahjub, Hujwiri teaches that the practitioners of every craft and discipline develop their own technical expressions and terms whose meaning is known only to insiders. He identifies two reasons for coining such specialized vocabulary: first, ease of instruction (حسن تفهیم) and the simplification of subtle, difficult matters (تسهیل غوامض) so that they come nearer to the disciple's understanding; and second, the concealment of the secret (کتمان سر) from those who are not people of that knowledge. He argues by analogy from the technical vocabularies of the lexicographers (اهل لغت), the grammarians (اهل نحو), and the prosodists (اهل عروض), each restricted to its own coined terms, that the Sufis likewise possess a proper terminology whose definitions and inner realities must be set out. This concept frames why an entire section of the book is devoted to defining Sufi expressions.