Ideas are slippery. Don’t think “that’s good, I’ll have to remember that” – you won’t. When you get a good idea, thought, or piece of information, write it down – on whatever paper is available. If it’s written on anything but a hardcover journal, transfer it to such a permanent book later that day. Capture the idea.
By writing it down, it helps you develop the idea, and be more clear. And by having a hardcover book, you’ll keep the idea safe for reference. Your book will become a cherished asset to you.