Flexibility (mudu) in the psychological sense is the quality of being able to see changes and nuances in a situation or principle and adjust to them accordingly. In the Metta Sutta, the Buddha advocates flexibility together with several other rarely discussed but important virtues, "One should be capable, straightforward, very straightforward, easy to speak to, flexible and modest" (Sn.143). In the Jataka he says, "Let one bend like a bow and be as pliant as bamboo, and then he will be at odds with none" (Ja,VI,295). The Buddha’s flexibility is most apparent in his attitude to rules. He made rules for monks and nuns to address specific problems and he expected everyone to take them seriously and to abide by them. However, he was wise enough to understand that no rule can cover every possible situation, that situations change and therefore that rules should be changed when necessary. In the Vinaya we see how rules were adjusted and modified and just before his passing the Buddha told his disciples that they could change minor rules when the need arose (D.II,154).