A very old complete copy of the Greek New Testament, Codex Sinaiticus, shows many signs of reader aids. One such feature is referred to as "ekthesis." A visual marker where the first sentence of a new paragraph or sense unit extends out into the left margin (Hurtado, 179). Codex Sinaiticus has many examples of this feature and in particular the story of Jesus' transfiguration in Mark 9 show extreme ekthesis (Head, 10). Here verses 9:4, 5, 7, 8, 9, and 10 are each marked off with an extreme out-dented "ΚΑΙ" (Head, 10).
A common feature in our modern printed and electronic text, spaces between words and sense units (sentences) were not so common in antiquity. Looking at the pictures above, one can see the use of spaces in marking the end of paragraphs just before the use of the "ekthesis." The use of spaces between words to mark punctuation can also be found in other manuscripts such as Codex W, a 4/5th century copy of the four gospels in Greek. Scholar Henry Sanders noticed the use of spaces to mark punctuation in Codex W and Codex Bezae, a 5th century copy of the New Testament in Greek (Hurtado, 180).
Many have taken to studying these traces of punctuation and paragraphing in these early manuscripts, to give our modern eyes a small picture into how these early Christians viewed, read and studied the New Testament in reading and worship.
Head, Peter. "The Gospel of Mark in Codex Sinaiticus: Textual and Reception-Historical Considerations." TC: A Journal of Biblical Textual Criticism. Vol. 13 (2008). http://rosetta.reltech.org/TC/vol13/vol13.html
Hurtado, Larry W. The Earliest Christian Artifacts: Manuscripts and Christian Origins. Grand Rapids: Eerdmans, 2006.