Draw a regular octagon. Use ruler and compass.
1) Draw a line, horizontal.
2) Construct another line, perpendicular to it at point A.
3) Draw a point crossing first line, B.
4) Draw a quarter circle centred at A, from B on horizontal line to D on perpendicular line.
5) Draw circular bows, more than quarter circle, from A, centred at B and D and call their meeting point C.
6) Draw lines DC and CB.
You should now have a square, ABCD(A) (counterclockwise from bottom left, for instance).
7) Draw quarter circle D to B centred at C.
8) Draw diagonals AC and BD.
9) Call meeting points of diagonals and circles EFGH, E being the one close to D and in opposite direction to ABCD (for instance clockwise from top left).
10)Draw lines EH and FG and extend them to points I and K on DC=DIKC and to points O and N on AB=AONB.
11) Draw lines EF and HG, extending them to Q and P on AD=APQD and to L and M on BC=BMLC.
12) Join IKLMNOPQ(I). Which is a regular octagon. QEF.
What is this?
From the four corners of the world (ABCD), God assembles his Church, founded on Patriarchs and Prophets, Apostles and Evangelists with Christ himself as cornerstone (cross EIKFLMGNOHPQ(E)), drawn in by the Tradition and doctrine of the four Gospels (EFGH), and it resembles the Arc of Noah, in which the eight ONLY survivors of the Flood were, insofar that outside it there is no Salvation. Its eight walls represent the living stones of the Temple of God, the faithful, who on the Arc of Noah were eight. One could cite eight testimonies of the resurrection, the Blessed Virgin Mary and the three women mentioned in the Gospel and the Four Evangelists who wrote the account, of which they or people they had talked to were witnesses. And one can cite the Four Great Latin and the Four Great Greek Church Fathers: St Augustine, St Jerome, St Gregory the Great, St Leo the Great, St Athanasius, St Basil the Great, St John Chrysostom and St John the Damascene - unless the great Greeks were the Three Great Cappadocians (St Basil the Great and St Gregory of Nyssa and St Gregory of Nazianz) and St John Chrysostom.
It is of course the ground plan of a Baptisterium.
Written by
Hans Georg Lundahl
in the Year of Our Lord MMII,
Oct. 7, Feast of Our Lady of the Rosary.