Passage in Seal Script - 18th C Japanese Book of Chinese Poems (Poem identified: 唐・賈至《西亭春望》)
In modern script:

唐　賈至　《西亭春望》
日長風暖柳青青　北雁歸飛人窅冥
岳陽城上聞吹笛　能使春心滿洞庭

With the character variants inserted in their place: