This is the 6277th most frequent Turkish word.
öylesine
"Just because," "casually," or "without a specific reason or purpose."
In this case, 'öylesine' is used to convey the idea that the action of buying the book was done in a casual, non-deliberate manner without a specific reason.
Bu kitabı öylesine aldım.
I bought this book just casually.
Here, 'öylesine' emphasizes the extent of how beautiful the weather was, serving as an intensifier.
Öylesine güzel bir hava vardı ki, dışarı çıktık.
The weather was so beautiful that we went out.
In this example, 'öylesine' indicates that the conversation is casual and does not carry significant importance.