A biologist, a doctor, an art dealer, and a cloth merchant acquire their expert knowledge in part from textbooks, but these texts are of no use to them without the accompanying training of hte eye, the ear, and the sense of touch. Only by attentively straining their senses can they acquire the right sense, or feel, for identifying a certain biological specimen, the symptoms of a certain sickness, a genuine painting by a certain master, or a fabric of a distinctive quality. By such training the expert develops an exceptional fastidiousness which enables him to act as an appraiser of the value or meaning of certain objects or conditions.Michael Polanyi
Polanyi continues “thus the observer’s participation in the act of knowing leads to a point where observation assumes the functions of an appraisal by standards which the observer regards as impersonal, i.e., generally applicable rather than personally idiosyncratic.”