Rough as a saw-edge, and hard as whinstone! The less you meddle with him the better.
Nelly warns Lockwood about Heathcliff with working-class clarity—no poetry, just texture you can feel. The tool-and-stone similes make Heathcliff sound useful and dangerous. She isn’t neutral; she’s protective of her ‘people’ and skeptical of strangers. This is Nelly at her best: plain speech that still carries judgment. Her line sets Lockwood’s expectations and primes us for violence under the roof. Her judgment carries both warning and a little pride in reading men clearly.