By protecting the nerve ending in he hand, the callous makes the act of probing less hesitant […] the callous both sensitises the hand to minute, physical spaces and stimulates the sensation at the fingertips.*
(Richard Sennett)

Prescriptive technologies constitute a major social invention. In political terms, prescriptive technologies are designs for compliance.**
(Ursula Franklin)

Callous can often mean insensitive, but it may also mean the exact opposite.

Richard Sennett writes about the hard skin at our fingertips but his insight can be translated to whatever skill we have practised and honed.

A callous is then a mark of much practise and experience, and possibly something that matters to us greatly and can potentially make a difference in the life of another.

A musician and a silversmith develop callouses but so does the person who uses questions to help and support others, for instance.

Ursula Franklin’s reflection on prescriptive technologies is concerned with acculturation, how our skills can be subsumed into a larger system. What then might happen is restriction of the development of our callouses, but, whether we work for ourselves or for others, these callouses are ours and the responsibility for developing them is ours too and we often evolve them in quite remarkable ways:

Imagination is more important than knowledge. For knowledge is limited, whereas imagination embraces the entire world, stimulating progress, giving birth to evolution.^

We might, then, understand callousness to be an attitude as much as a mark of talent.

(*From Richard Sennet’s The Craftsman.)
(**From Ursula Franklin’s The Real World of Technology.)
(^Albert Einstein, quoted in Ben Hardy’s These 20 Pictures Will Teach You More Than Reading 100 Books.)