the post card is a replication of a painting, which is in the palace museum (故宫博物院). imo, the quality is, unacceptable. here's a better image of the painting:

about the text, traditionally, one read from top to bottom, right to left. so, the rightest text are:
南刻京喬
宋畫口柯
諸之山急
公跡樓澗
皆為待唐
拜之風解
牀一觀元
下變六有
洗如此
惲其卷景
壽勾筆因
平砍墨倣
煥靈其
然逸意
神李
明唐
當
使
it was written by the painter 惲壽平, as a "preface". the meaning of it, roughly is:
喬柯急澗
tall and bent (喬) branch [of tree] (柯), torrential (急) stream (澗)
used as the subject of the painting.
唐解元有此景因倣其意
"解元", "六如居士" were referred to 唐寅, a painter of ming dynasty.
mr 唐 (唐解元) had (有) this (此) scene (景, --> similar painting of 喬柯急澗), therefore (因) [ i ] simulate (倣) his (其) ideas (意)
京口山樓待風.觀六如卷
in 京口 (a place name), on a tower / building (樓) in the hills (山); waiting for (待) wind (風) [--> to cool off], read (觀) mr 唐's (六如) scroll (卷)
筆墨靈逸.李唐刻畫之跡.為之一變.洗其勾砍.煥然神明
the strokes (筆墨) were deft (靈), with leisure (逸). the trace (跡) of (之) stubborn (刻畫) of mr 李 (李唐, a painter of 宋 dynasty), changed significantly (為之一變). removed (洗) his (其) "strike out" (勾) [and] chop (砍); changed to (煥然) outstanding & bright (神明)
當使南宋諸公皆拜牀下
[which] should (當) make (使) painters (諸公) of the southern song dynasty (南宋), all (皆) bow (拜) under (下) [his] stand (牀, a variant of 床, which should be interpret as 安放器物的架子, not bed).
惲壽平
the painter's full name
then, the text on the left, was a poem written by the emperor 乾隆 :(
it was recorded in 御製詩三集 卷九十四, page 82:
https://archive.org/stream/06078952.cn#page/n81/mode/1up
即設澗喬
今使水柯
誰不籦嶰
識經籠壑
馬裁潄臨
融作趾急
才笛哀澗
well, poem should be interpret by oneself :)
have fun :)
anyone want to decipher the seals?