The Sutra of True Profit and True Cost
Thus have I heard: Once, the Buddha dwelt at Sravasti, in the walled garden of Jeta, and there was a gathering of great Bhikkhus and great Arahats. Assembled were the elders and the boddhisatvas and the gods, numberless in multitude.
The Blessed one told Sariputra, “How great a release it is to know the true cost and the true profit. For there are those who count costs and count profits, but counting falsely, fall into despair, and cling on to false attachments.
“Sariputra, costs that are spent cannot be thought of as unspent. These are sunk costs. For what reasons are they called sunk costs? For it is as though they have sunk into the oceans and returned to the depths. They are no longer personal costs, and their significance have melted away.
“Sariputra, letting go of sunk costs, the rational one will not be aggrieved by the losses they have made in the past. Any actions they committed in the past, and committed to them in the past have no bearing on their actions in the present. Rather, the rational one reflects only on the marginal cost and profit of any additional actions they make.
“Moreover, Sariputra, they will not be pained by the passing of love, or of their youth, or of their fame, or of their riches, for they shall reflect that none of that is theirs any longer, and none of that affects the marginal utility of their present decision set.
“That is not to say, Sariputra, that past actions should be disregarded. Insofar as they update the current information set, they can affect beliefs of the probabilities of the distribution of utility of a decision set.
“Sariputra, the rational ones will not be jealous, for they will understand that the possessions and welfare of others are not necessarily in zero-sum with their own welfare.
“And if an action is no longer in their decision set, what need have they to be anxious? The rational ones shall reflect on what they can do, not what they could have done, Sariputra.
“There are those who use historical cost to assess the value of assets. Why do they do this, Sariputra? For accounting purposes, a conservative evaluation is borne out of wisdom. But for due diligence purposes, an estimation of net present value will be more informative.
“Sariputra, what peace is there for those who know true cost and true profit. For most anxieties of sentient beings are anxieties for that which they cannot help, and cannot remedy, and cannot increase or decrease. They are anxious over the illusory; things that not only shall pass, but have already passed.
“Sariputra, you know that the rational ones will still be subjected to behavioural cues, priming and fallacies of thought, but if they consciously hold the mantra of true cost and true profit in their hearts, they will find at last unconfusion.”
And after the Buddha spoke this sutra, Sariputra and all the bhikkhus, all the gods, men, and those from all the worlds, hearing what the Buddha had said, joyously welcomed, faithfully accepted the teaching. They bowed and withdrew.
