Comparing and contrasting instances of the phenomenon lead to the discovery of similarities and differences. For instance, in studying patients' crying it was found that their crying was with or without tears; loud or silent; expressing pain, anger, fear, sorrow. Or again, silence may be defined simply as absence of sound. But silence as experienced in the real nursing world has other characteristics. It may convey anger, fear, peacefulness, and so forth. It is these nuances or qualities of silence that are significant cues for the nursing dialogue. They could be brought to light by comparing and contrasting descriptions of silence. Various instances of the phenomenon being studied may be examined to discover common elements. Characteristics or elements seen in one instance are sought in the others. For example, when descriptions of interpersonal empathy were scrutinized, it became evident that in all cases there were physiological, psychological, and social components. Examining experiences {83} of reassurance revealed they had elements such as empathy, sympathy, reality orientation, feelings of hope and comfort. One may determine which elements are essential to the phenomenon by imaginative variation, that is, by trying to imagine the phenomenon without a particular element. For instance, reassurance without empathy or sympathy would be false reassurance or, in other words, would not reassure. The elements of the phenomenon can be studied to determine how they are interrelated. One may ask, is there a priority in time? Does one element develop from another? Consider the phenomenon of reassurance; does empathy precede sympathy? Or, to take another example, in the empathic experience, an openness to the other and an imaginative projection into his place lead to the vicarious experiencing of his situation. For further clarification of its distinctive qualities the phenomenon may be related to and distinguished from other similar phenomena. For example, empathy is similar to and also different from identification, projection, compassion, sympathy, love, and encounter. By considering what it has in common with other phenomena, the phenomenon being described may be classified as being subsumed in a broader category. Thus, empathy is a human response, a coalescent movement, a form of relating. The phenomenon may be described by selecting its central or decisive characteristics and abstracting its accidentals. For instance, interpersonal empathy always involves movement into another's perspective and as a form of movement it has directions, dimensions, and degrees. It can occur between persons of difference age, education, experience, sex; these latter characteristics are accidental. Some descriptions make use of negation. A phenomenon cannot be described completely by negation but it may be clarified to some extent by saying what it is not. For instance, empathy is not sympathy; it is not projection; it is not identification.