For although canvas and paint develop their rhetoric only out of silence and it is precisely through motionlessness that the man wrapped in his philosopher's coat importunes us, at every moment this collected silence turns into speech and a loud motto.

キャンバスと絵の具は沈黙からしかそのレトリックを展開することはないし、それはまさにこの哲学者の外套に身を包んだ男が我々に要求する静止を通じてであるけれども、絶えず、この集まった沈黙がスピーチや騒々しいモットーに変化を遂げる。

http://en.wikipedia.org/wiki/File:SPSalvatorRosa.jpg
Salvator Rosa, self-portrait, 1640.
"Either shut up, or say something better than silence [i.e. something worth saying]" says the inscription. (「哲学者としての自画像」　＊左下の碑文に「黙っているか、または何か価値のあることを言え」とあります)

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"In an article that deals specifically with Rosa's self-portraits, Roworth claims the work titled Self-portrait as a Philosopher is actually a depiction of "silent rhetoric." Roworth rejects the idea that this work is an idealized self-portrait; however, she states toward the end of her article, "[Self-portrait as a Philosopher] may be considered an idealized, allegorical self-representation, a 'speaking picture'…." In this sentence, Roworth perfectly explains the concept of the "notional" self-portrait. Rosa was not trying to paint accurate depictions of his face or body, he was painting statements of his personal beliefs. The two works described in this section illustrate his identity and character; within this context, these two works epitomize the notional self-portrait."

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"Salvator Rosa was the consummate artist, or at least he thought of ..."
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