Reflections upon some Persons and Things in Ireland is an essay, written by Sir William Petty (1620-1687) and published in 1660. It contains a summary of the work carried out by Petty in the so called 'Down Survey', and especially a defense against the critics that were cast upon him afterwards. It was a further elaboration of the short pamphlet, titled The Proceedings between Sankey and Petty, that was published by Petty the year before.