Looking on the internet deeply has found these results:

in theory is the most popular phrase on the web.

from theory 16,300,000 results on the web	in theory 11,140,000,000 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
Unfortunately it took the Lisbon process, some six years later, to grab this opportunity and I am delighted that we have now moved from theory into practice. Conservation agriculture: from theory to practice. Your laboratory instruments from theory to practice. We will now pass from theory to practice... Today we are moving from theory to practice. The transition from theory to practice is slow and cumbersome. To go from theory to practice, I have some difficult questions to ask. Clinical Assessment in Autism: from theory to practice	Americans themselves are discovering that unlimited choice seems more attractive in theory than in practice. I'm a great cook The office of Governor was also, in theory, made hereditary. School teachers distinguished medicine in theory and practice. Most people subscribe to this in theory but not in practice. in theory. But in theory, he should still be a frozen head. This attitude, which in theory suits all parties, is quickly stigmatized.

from theory

16,300,000 results on the web

in theory

11,140,000,000 results on the web

More popular!

Unfortunately it took the Lisbon process, some six years later, to grab this opportunity and I am delighted that we have now moved from theory into practice.
Conservation agriculture: from theory to practice.
Your laboratory instruments from theory to practice.
We will now pass from theory to practice...
Today we are moving from theory to practice.
The transition from theory to practice is slow and cumbersome.
To go from theory to practice, I have some difficult questions to ask.
Clinical Assessment in Autism: from theory to practice

Americans themselves are discovering that unlimited choice seems more attractive in theory than in practice.
I'm a great cook
The office of Governor was also, in theory, made hereditary.
School teachers distinguished medicine in theory and practice.
Most people subscribe to this in theory but not in practice.
in theory.
But in theory, he should still be a frozen head.
This attitude, which in theory suits all parties, is quickly stigmatized.