About This Answer
How can one be sure of contemplating the body's repulsiveness correctly, given that some monks in the Buddha's time took their own lives? Ajahn Dtun asks why attention goes to those few, when many thousands since have realised the Dhamma through this practice, and warns that the defilements look for ways to block the path. Where mindfulness, concentration or skilful means are lacking, advice from a teacher may be needed.
He notes that a preceptor gives the five basic kammaṭṭhāna at ordination: head hair, body hair, nails, teeth and skin, reflected on forwards and backwards. Those not suited to body contemplation can start with its external aspects. Unwashed hair turns oily, and a fallen hair is lifeless earth; in food it spoils the meal. Skin sweats and soils clothing, and a wound releases blood and pus, suggesting what lies beneath the whole skin. With firm mindfulness and concentration, one may go on to see the body break down into its elements and finally into emptiness.