There has been an association betwe

There has been an association between the heat and piquancy of mustard and the zest and energy of people's behaviour. This dates back to at least 1672, when the term 'as keen as mustard' is first recorded. 'Up to mustard' or just 'mustard' means up to standard in the same way as 'up to snuff'. 'Cutting' has also long been used to mean 'exhibiting', as in the phrase 'cutting a fine figure'. Unless some actual evidence is found for the other proposed explanations, the derivation of 'cutting the mustard' as an alternative way of saying 'exhibiting one's high standards' is by far the most likely.