In Chapter Two of The Little Guide To Your Well-Read Life, Steve Leveen reasons why readers should mark up their books. Leveen described "those who write in books as Footprint Leavers and those who do not as Preservationists."Important writers, even mathematicians, have contributed significantly to the role of marginalia, he notes. For examples, visit www.yourwellreadlife.com/footnote.
Local libraries frown on personalizing reading material, and in deciding which donated books to shelve in their collections––annotated copies will, most likely, go elsewhere. You need to know this if you intend to donate books filled with notes and comments. On the other hand, consider the largesse of meaning those scribbles and notes might hold for an unassuming reader––cryptic thoughts, feelings, and opinions, or Aha! moments waiting to be discovered by a fresh eye.
One verse from Billy Collins's poem, Marginalia, www.poemhunter.com sizes it up:
We have all seized the white perimeter as our own
and reached for a pen if only to show
we did not just laze in an armchair turning pages;
we pressed a thought into the wayside,
planted an impression along the verge.
Consider, also, Harvard University's open collections' program on reading and marginalia: http://ocp.hul.harvard.edu/reading/marginalia.html
Marginalia provide unique records of the reader’s experience. Offering insights into how and why a reader reads, marginalia take many forms. These range from glosses on difficult words or passages and lengthier notes on the meaning of a text, to illustrations and personal marks used to denote passages of particular interest. While marginalia are often highly systematic, they are also as individualistic: every reader’s engagement with a text is unique. Marginalia shed light on the mental, emotional, and intellectual process of reading, as well as changing historical patterns of reading practice.