1 must come at the end because it is contrasting a specific feature of print-reading and mind-reading. Before 1, we must have the ideas of print reading and mind-reading introduced to us. 41 is definitely a pair because, and we must introduce mind-reading before statement 4. The point is should we have 2 or 3 as the opening sentence? 2 has a better introductory tone, and statement 3 goes into the detail of mind-reading. Thus we must 23 as one pair and 41 as the other, with 23 coming first. 2341 is thus the right sequence.