"Professional offices" means offices maintained and used as a place of business conducted by persons engaged in the healing arts for human beings, such as physicians and dentists (but wherein no overnight care for patients is given), and by engineers, attorneys, architects, accountants and other persons providing services utilizing training in and the knowledge of mental disciplines as distinguished from training in occupations requiring mechanical skill or manual dexterity or the handling of commodities. (Ord. 523 § 1(part), 1989)