The Borromean rings as a symbol of the Christian Trinity.  Drawn from scratch (not scanned), based on an illustration in a 13th-century French manuscript found at Chartres, as reproduced in Didron's book "Christian Iconography" (1843).  TRINITAS (trinity) is around the edge, and UNITAS (unity) in the center (see external link http://www.liv.ac.uk/~spmr02/rings/trinity.html ).
SVG version of Image:BorromeanRings-Trinity.png .
Converted from the following PostScript code (note that this program references the "Zapf Chancery Medium Italic" font, which is part of the Basic 35 PostScript fonts, but not the Basic 14):

%!
/y{240 120 3 sqrt mul sub}def
/d1{gsave
30 setlinewidth
0 setgray
stroke
grestore
stroke}def
/d2{0 setgray
5 setlinewidth
-37 540 280 260 290 arc
158.641736 243.625292 105.268881 161.581249 206.581249 arc
3 90 123 60 120 arc
-153.820991 197.648753 95.327902 -0.6778395 44.3221605 arc
closepath
gsave
1 setgray
fill
grestore
stroke
120 rotate
37 540 280 250 280 arc
153.820991 197.648753 95.327902 135.67784 180.67784 arc
-3 90 123 60 120 arc
-158.641736 243.625292 105.268881 -26.581249 18.418751 arc
closepath
gsave
1 setgray
fill
grestore
stroke}def
/bx{newpath ulx uly 5 270 0 arcn
ulx uly hit sub 5 0 -270 arcn
ulx wid add uly hit sub 5 90 180 arcn
ulx wid add uly 5 180 -90 arcn
closepath stroke}def
1 setlinejoin
77 320 translate
0.75 dup scale
18 setlinewidth
1 setgray
306 240 240 0 360 closepath arc d1
gsave 306 240 translate
90 rotate d2 grestore
186 y 240 0 360 arc closepath d1
gsave 186 y translate
-150 rotate d2 grestore
426 y 240 0 360 arc closepath d1
gsave 426 y translate
-30 rotate d2 grestore
30 setlinewidth
0 setgray
306 240 240 -10 9 arc stroke
306 240 240 231 250 arc stroke
18 setlinewidth
1 setgray
306 240 240 -11 10 arc stroke
306 240 240 230 251 arc stroke
0 setgray
/ZapfChancery-MediumItalic[84 0 -8 84 0 0]selectfont -10 -9
moveto(t)show 3.5 0 rmoveto(r)show 6.5 0 rmoveto(i)show 2 .5
rmoveto(-)show 265 350 moveto(n)show 5 0 rmoveto(i)show 2 .5
rmoveto(-)show 515 -8 moveto(t)show 3 0 rmoveto(a)show 7 0
rmoveto(s)show/ZapfChancery-MediumItalic[63 0 -6 72 0 0]
selectfont 236 77.5 moveto 1.5 0(unita)ashow 3 0 rmoveto(s)
show
3 setlinewidth
/ulx -16 def/uly 54.5 def/wid 126 def/hit 77 def bx
/ulx 256 def/uly 413.5 def/wid 111 def/hit 77 def bx
/ulx 509 def/uly 46 def/wid 119 def/hit 67.5 def bx
showpage
%EOF
AnonMoos