There are two methods of mental conclusions: 'formation' and 'formulation'. 'Formation' is a conclusion arrived at by the way of least resistance, avoiding difficulties. It is easier because it makes itself—ready-made phrases, ready-made opinions, like a stamp. It is generally defective with the exception of the simplest cases. 'Formulation' is a conclusion arrived at on the basis of all the available material; it needs effort and is sometimes difficult, but it means the best we can do