learn from the bottom up
learn (something) from the bottom up
1. To learn or become knowledgeable about every or nearly every aspect of something, from the most mundane to the most nuanced. After working at this company for nearly 30 years, I've learned it from the bottom up. As the chief tax law specialist, it's my role to learn these new tax regulations from the bottom up.
2. To become knowledgeable about or skilled in something by beginning at the most basic level and then working one's way up to the more complicated or difficult aspects. I actually never had any sort of preternatural skill with mathematics—I had to learn it from the bottom up, just like most other students. I hard forgotten everything I knew about Japanese, so when I started studying it again in my 30s, I had to learn it from the bottom up all over again.
learn something from the bottom up
Fig. to learn something thoroughly, from the very basics; to learn all aspects of something, even the least important ones. I learned my business from the bottom up. I started out sweeping the floors and learned everything from the bottom up.