Syag, I mean R Avraham Yehoshua Twersky Z’L, the psychologist. Thanks to your question, I revisited the story I thought I knew and it turns out more complicated:
Rav Twersky wrote to his mentor The Steipler in 1955 asking for his advice on choose a profession. I saw several sources descriving the letter a little different. Maybe someone has access to the published letters and can confirm. Most of below comes from seforimblog Feb 2021:
He asked wither whether he should go to medical school or a general question about a non-Rabbinical profession. The Steipler replied that medicine is preferred as it is a mitzva to learn it and is excluded from Rashba’s ban on secular knowledge. He suggested being stringent in – learn in depth at least two hours a day; attend all minyanim; go regularly to the mikva; be strict about Shabbos – not to read secular/science literature, learn musar daily.
There was a second letter, where R Twersky asked about his choice of being a Rabbi in low-observance community (and impact on his children) or being a doctor. The Steipler replied that rabbinate is preferred, but that R Twersky will become also become a successful physician (and it will make his observance even more challenging). R Twersky got from this that he went to be a doctor “with The Steipler’s blessing”.
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