縁は弦と接し、硬直性はローテーション (曲がりくねり) と出くわす

- Even in English, this looks abstract, especially if one is unfamiliar with the self-portrait of which it is describing. Without your helpful reference, I would scratch my head and say: “Huh?”

- However, it does make sense after seeing Bacon’s self-portrait. (His art is truly masterful and I do admire them, but they always give me the creeps!)

(1) [Edges meet chords:]
- The floorboards in the light brown circular section of the painting form many “chords” ((円の弦)
- These floorboards (the chords) meet (or:“touch”) the “edge” of the floor and the "edge" at bottom of the wall. [the two edges meet]

Please see an illustration of a “geometric chord” in the website below (English & Japanese):
http://en.wikipedia.org/wiki/Chord_(geometry)
http://ja.wikipedia.org/wiki/円_(数学)#.E5.86.86.E3.81.AE.E6.80...

http://ja.wikipedia.org/wiki/円_(数学)#.E5.86.86.E3.81.AE.E6.80...
さらに円の弦についても様々な性質がある。

(2) [Rigidity meets rotation:]
- There is “rigidity” in the straight lines (examples: in the straight floor boards, and in the two large rectangular blocks in black and in purple.) - The “rotation” is represented by the curvilinear shapes in the chair and the table legs, and the contorted curving twists of Francis Bacon’s body.

(My bizarre analogy is: it’s like the rigid, square-shaped Incredible Hulk meets Plastic Man.)

http://ja.wikipedia.org/wiki/ローテーション
ベクトル解析で扱われる概念で、「回転」ともいう。 数学の諸分野や物理学（特に流体力学、電磁気学）などで応用される。→回転 (数学)

http://en.wikipedia.org/wiki/Rotation_(disambiguation)
Generally, it is used to denote (in 3D) the rotation of movement of a rigid body in such a way that any given point of that body remains at a constant distance from some fixed line (in 2D: point).



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Note added at 23 hrs (2010-07-02 11:34:41 GMT)
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I am glad it makes sense, Jack. :-)

I just realized I gave you the wrong website on one. I had given you the "ja.wikipedia" site twice.) So, here it is again.....(Though the site isn't that important to the question.)

http://contest.thinkquest.jp/tqj1998/10064/text/en.htm
さらに円の弦についても様々な性質がある。