A connoisseur is defined as “one who understands the details, technique, or principles of an art and is competent to act as a critical judge.” What do those words actually mean? The word “connoisseur” looks French and is indeed related to the French verb connaître, “to know.” An art connoisseur must know when and where an artwork was created. Must be able to recognize not only the work of one artist but also the work of other artists active at the same time in the same area. Must know the stylistic differences that distinguish one from the other. 
But connoisseurship is more than simply knowing. Connaître‘s ancestor is the Latin word cognoscere, or co-gnoscere: with — recognition or knowledge. That root – recognition -- reaches to the heart of the connoisseurship. Art connoisseurship implies a degree of learning and experience that allows a connoisseur almost intuitively to recognize the work of a particular artist.
Inferred in co-gnoscere is understanding. An understanding that there is always more to be learned or tested. Without this compassionate knowledge, an art expert can become an egotistical connoisseur. True connoisseurship includes the humility of wisdom. In the words of a lion of connoisseurship, Max J. Friedlander, “even a highly regarded and experienced dealer can no longer say to his customers: ‘I regard the picture as a work by Titian and assume the guarantee; there is no need for an expert opinion.” He went on to say, in effect, increasing the power of an expert, increases the danger of misuse of power. Honest connoisseurs, even with the recognition of experience, verify the facts of provenance and incorporate scientific examination.
1. Merriam Webster, “Connoisseur,” https://www.merriam-webster.com/dictionary/connoisseurship
2. Suzanne Laemers, “Max J. Friedländer and the Essence of Connoisseurship,” Codart eZine, EZINE 7 WINTER 2015, http://ezine.codart.nl/17/issue/55/artikel/max-j-friedlander-and-the-essence-of-connoisseurship/?id=325#!/page/1, accessed February 2019.
3. Max J. Friedlander, On Art and Connoisseurship (Beacon Press, 1960), 204