Plot on the co-ordinate plane the two path of the saint- Y-axis being time, X-axis being height.
First day's path should be a curve that goes UP from (0,0) to (T1, Height) with a continuous positive/zero slope.
Second day's path should be a curve that goes DOWN from (0, Height) to (T2, Heigh), with a continuous negative/zero slope
Since both these curves are continuous and their slopes don't change direction (the saints don't time-travel yet), they will have to intersect at some point - that is the point where they were at the same place, at the same time!
A great primer for anyone starting on the journey of coaching teams. I think the title is a little disservice to the content of the book - the book not only talks about coaching Agile teams.. though the result of such coaching would like...