Boulanger had as many as 40 students at once and employed a formal regimen that Copland had to follow. Copland found her incisive mind much to his liking and found her ability to critique a composition impeccable. Boulanger "could always find the weak spot in a place you suspected was weak... She could also tell you "why" it was weak Copland." He wrote in a letter to his brother Ralph, "This intellectual Amazon is not only professor at the Conservatoire, is not only familiar with all music from Bach to Stravinsky, but is prepared for anything worse in the way of dissonance. But make no mistake ... A more charming womanly woman never lived." Copland later wrote that "it was wonderful for me to find a teacher with such openness of mind, while at the same time she held firm ideas of right and wrong in musical matters. The confidence she had in my talents and her belief in me were at the very least flattering and more—they were crucial to my development at this time of my career." Though he planned on only one year abroad, he studied with her for three years, finding her eclectic approach inspired his own broad musical taste.