One of the biographical studies on Shakespeare is to prove how he was influenced by Italian Renaissance. It has not been sufficiently studied. The chain which connects Shakespeare with Giordano Bruno, a most influential Italian philosopher of the day, remains to be researched. In the process of tracing of the originality of Shakespeare's favorite metaphors such as "shadow", "infinite universe", "world's stage" and others, I have reached the conclusion that Shakespeare must have been influenced by Bruno. The influence, however, is not direct one but through the filter of what is called the literary people called the Sidney Circle. Bruno was introduced to Sir Philip Sidney by John Florio, one of the members of the literary people patronized by Mary Sidney, the Countess of Pembroke, Philip's younger sister. Bruno associated with the members of the Sidney Circle at the French Embassy in London where he stayed for two and half years, while lecturing his philosophy. In the interchange with them five of his main works were written and published in London. Two of them were dedicated to Philip Sidney. After Philip was killed in the war, most of the members flew to his sister, the Countess of Pembroke's Circle. She was a leading woman writer, the greatest patroness of literature and presided over the biggest literature Circle in the Elizabethan age. There were many famous men of letters such as Fulke Greville, Florio, Thomas Sackville, Ben Jonson, Edmund Spenser, Michael Drayton and others in her Circle.

　I got most of materials such as the microfilm of a doctoral dissertation of 70 years ago and the trial records on the Earl of Essex in the Cambridge University Library. At first historically and literally I focused on Shakespeare and Mary Sidney, and demonstrated on the connection between Shakespeare and the Countess of Pembroke's Circle. And next by tying evidence one after another, I proved that Bruno contacted with the Sidney Circle. Basing on this careful research, I state how the influence of Bruno's philosophy and idea flew into Shakespeare and how it materially appears in Shakespeare's plays.

　In consequence, though Shakespeare may not have met Bruno and may not have been influenced by Bruno directly, there was the medium called the Sidney Circle between them. Shakespeare must have touched Bruno's philosophy through the members of the Sidney Circle and their works.

シェイクスピアとシドニー・サークル：英国ルネサンス期におけるジョルダーノ・ブルーノの影響

　シェイクスピアの伝記的研究のひとつに、イタリア・ルネサンスの哲学とシェイクスピアを繋ぐ鎖の研究があるが、その鎖は今まで繋がらず曖昧のままであった。彼の作品の底に流れている哲学は、独自に生み出されたものなのか、それとも誰かから何らかの影響を受けたものなのだろうか。多くの作品に顕著に出てくる「影」「無限の宇宙」「世界劇場」などの系譜を辿るうちに、イタリアの哲学者ジョルダーノ・ブルーノに辿りつく。しかしブルーノから受けた影響は直接的なものではなく、シェイクスピアとブルーノの間には二人を結ぶ媒体があった。ブルーノが招かれたフィリップ・シドニーのサークルと、フィリップの死後そのメンバーが流れていった妹メアリー・シドニー, ペンブルク伯爵夫人の文芸サークルである。彼女はエリザベス朝の文芸の最大の擁護者で、彼女の文芸サークルにはイギリス・ルネッサンス期の著名な文人たちがこぞって集まっていた。

　本書では、ブルーノとシドニー・サークルの接触、サークルとシェイクスピアの結びつきを論証し、結果として、ブルーノの思想と哲学の影響がいかにシェイクスピアに流れ、具体的にどのように現れているかを作品に即して論考したものである。