How did Paul Ehrlich conclude without testing disinfectants?

Paul Ehrlich concluded the efficacy of certain compounds as disinfectants through a process known as "chemical intuition" and extensive empirical observations rather than direct testing. He hypothesized that specific chemical structures could target pathogens effectively based on their anatomical and physiological characteristics. This approach, alongside his work on the "magic bullet" concept, allowed him to propose potential disinfectants that would later be validated through experimental methods. His innovative thinking laid the groundwork for modern pharmacology and antimicrobial treatment.