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'The Pine tree (Matsu) symbolizes long life, and it is believed that after a thousand years its sap turns to amber; but it also implies other things, sturdiness and strength and steadfastness. Again, two Fir trees standing side by side (more especially the famous two at Takasago and Suminoye, of the popular old Nö drama) typify a husband and wife growing aged together.'
Japanese Gardens, page 142