《教育科學的資源》: The history of the more mature sciences shows two chayracteristics. Their original problems were set by difliculties that offered themselves in the ordinary region of practical affairs. Men obtained fire by rubbing sticks together and noted how things grew warm, when they pressed on each other, long before they had any theory of heat. Such everyday experiences in their seeming inconsistency with the phenomena of flame and fire finally led to the conception of heat as a mode of molecular motion. But it led to this conception only when the ordinary phenomena were reflected upon in detachment from the conditions and uses under which they exhibit themselves in practices. There is no science without abstraction, and abstraction means fundamentally that certain occurrences are removed from the dimension of familiar practical experience into that of reflective or theoretical inquiry. To be able to get away for the time being from entanglement in the urgencies and needs of immediate practical concerns is a condition of the origin of scientific treatment in any field. Preoccupation with attaining some direct end or practical utility, always limits scientific in quiry. For it restricts the field of attention and thought, since we note only those things that are immediately connected with what we want to clo or get at the moment. Science signifies that we carry our observations and thinking further afield and become interested in what happens on its own account. Theory is in the end, as has been well said, the most practical of all things, because this widening of the range of attention beyond nearby purpose and desire eventually results in the creation of wider and farther-reaching purposes and enables us to use a much wider and deeper range of conditions and means than were expressed in the observation of primitive practical purposes. For the time being, however, the formation of theories demands a resolute turning aside from the needs of practical operations previously performed. ……