The characters are 白云長滿目, which roughly translates to
The vast expanse of white clouds, filling one's sight,
coming from the poem 《送廬山人歸林慮山》 by the Táng Dynasty poet Huángfǔ Rǎn.
「云」 is particularly difficult to identify, and is worthy of some additional explanation.
「云」 (Baxter-Sagart OC: /*[ɢ]ʷə[r]/, clouds) is comprised of semantic 「𠄞」 (up/above, now written 「上」) and phonetic
(/*[ɢ](r)ə[r]ʔ/). This character is 「旬」 before the addition of a 「日」 component.
Occasionally, the 「𠄞」 part of 「云」 may be partially or fully omitted, and the remainder may be rotated or distorted in some way. This forms the inspiration behind
which is the shape in the seal.