Different folks have different attitudes about marking in books.
Myself - I'm a book marker.
When I read a book - especially a nonfiction book - I usually do so with a pencil in hand. I underline favorite passages, make notes in the margins, and jot down questions that come to mind as I read. If I come across an unfamiliar word, I'll look up the definition and write that in the margin, too. Sometimes, I'll make a note of the date and particular circumstances in my life at the time.
Occasionally, something I read is particularly relevant to a problem or struggle I am currently facing. I make note of that, too. When I go back and reread a text a year or two later, it is interesting to see where I was then, and to consider where I am now.
At least one of my children has picked up the book marking habit. This turns the rather solitary act of quietly reading a book into a conversation that transcends time and place. For example, in G.K. Chesterton's Orthodoxy, my daughter occasionally commented on the notes I had written in the margin. Now, when I read through Orthodoxy again (a book every one of you should read at least once!), I encounter not only Mr. Chesterton's thoughts, but my own thoughts from the past and my daughter's thoughts as well.
I read my Bible with a pencil in hand, too. Reading through Scripture year after year, and documenting my life in a small way as I do, the Bible becomes my own story in a very real way.
Every time I read Psalm 91:15-16 - When he calls to me, I [God] will answer him; I will be with him in trouble; I will rescue him and honor him. With long life I will satisfy him and show him my salvation. - every time I read that passage, I see the note in the margin - 5-29-11/Melissa - and I thank God for bringing a sweet friend through a terrible illness and adding years to her life here on earth. Three and a half years ago, I read that passage with pleading and with tears in my eyes (Please, Lord!); today, I read it with joy and thanksgiving for God's mercy and goodness.
One of my children thinks that marking in any book - and especially the Bible - borders on sacrilege. I, on the other hand, think that books talk to us. Jotting down thoughts and notes in a book transforms a manuscript into a conversation between me and Mr. Chesterton or Mr. Lewis or my heavenly Father, and with the person who pulls a book off my shelf to read it after me.
Books and I - we've had so many lovely conversations!
How about you? Are you a book marker, too?
2 days ago