先(xian)天(tian)(tian)功(gong)(gong),武俠(xia)小說(shuo)中(zhong)絕學。《射雕英雄傳》中(zhong)是(shi)「中(zhong)神通」王重(zhong)陽(yang)的(de)絕學。而(er)其(qi)他書中(zhong)解釋為呼(hu)(hu)吸吐納(na)的(de)練功(gong)(gong)之法,講(jiang)究(jiu)抱元守一,欲練此(ci)功(gong)(gong),身(shen)如處子(zi),不(bu)(bu)動(dong)如山(shan),動(dong)如脫(tuo)兔(tu),呼(hu)(hu)先(xian)天(tian)(tian)下(xia)之憂(you)而(er)憂(you),后天(tian)(tian)下(xia)之樂(le)而(er)樂(le)。修(xiu)真活計有何憑,心(xin)死群情今(jin)不(bu)(bu)生。精氣充盈功(gong)(gong)行(xing)具,靈(ling)光照耀滿神京,秘語師傳悟(wu)本(ben)初,來時(shi)無(wu)欠去無(wu)余(yu)。神則(ze)守,身(shen)則(ze)守,此(ci)功(gong)(gong)乃道家獨門(men)不(bu)(bu)傳之秘,以祛(qu)百病、調虛實,治療沉重(zhong)內(nei)傷。此(ci)功(gong)(gong)極(ji)(ji)耗內(nei)力(li),需(xu)以高深內(nei)功(gong)(gong)為輔方可學之,當(dang)達(da)于極(ji)(ji)限時(shi),能相觸(chu)無(wu)聲(sheng),空中(zhong)暗勁橫流,風力(li)激蕩,功(gong)(gong)法里(li)的(de)奧秘能使人潛能意識(shi)被激發到(dao)極(ji)(ji)限,武學自會步入(ru)深不(bu)(bu)可測之化境。
在(zai)(zai)(zai)金庸最初的(de)(de)小說創(chuang)(chuang)作中,「先天(tian)(tian)功(gong)」是(shi)「南(nan)(nan)帝」段智(zhi)興的(de)(de)絕學,而「中神通」王重陽(yang)(yang)的(de)(de)絕學卻(que)是(shi)「一陽(yang)(yang)指(zhi)」。后來創(chuang)(chuang)作《天(tian)(tian)龍(long)(long)八部》將(jiang)(jiang)「一陽(yang)(yang)指(zhi)」改(gai)成(cheng)「大理段氏」武學。因(yin)此,在(zai)(zai)(zai)修訂時(shi)(shi)《射雕英(ying)雄傳(chuan)》、《神雕俠(xia)侶》、《倚天(tian)(tian)屠龍(long)(long)記》、《天(tian)(tian)龍(long)(long)八部》這四(si)部小說時(shi)(shi),為(wei)了能(neng)夠前後呼應,互相對照,特意(yi)將(jiang)(jiang)王重陽(yang)(yang)與(yu)(yu)段智(zhi)興的(de)(de)絕技交(jiao)換,曾打敗(bai)「西毒(du)」歐(ou)陽(yang)(yang)鋒(feng)(feng)的(de)(de)王重陽(yang)(yang)傳(chuan)之以法,將(jiang)(jiang)「先天(tian)(tian)功(gong)」以「一陽(yang)(yang)指(zhi)」使出,以剋(ke)制「蛤蟆功(gong)」,以免(mian)造成(cheng)段智(zhi)興在(zai)(zai)(zai)第一次「華山(shan)論劍」時(shi)(shi),身負能(neng)夠克制「西毒(du)」歐(ou)陽(yang)(yang)鋒(feng)(feng)的(de)(de)武功(gong)卻(que)只是(shi)與(yu)(yu)「西毒(du)」戰(zhan)成(cheng)平手的(de)(de)古怪結果。王重陽(yang)(yang)徒弟「全(quan)真七子」跟師(shi)弟「老頑童」周伯通均未獲(huo)得傳(chuan)授(shou),僅與(yu)(yu)「南(nan)(nan)帝」段智(zhi)興交(jiao)換過「一陽(yang)(yang)指(zhi)」,用意(yi)是(shi)要(yao)「南(nan)(nan)帝」擁有剋(ke)制「西毒(du)」歐(ou)陽(yang)(yang)鋒(feng)(feng)之能(neng)。「先天(tian)(tian)功(gong)」配合「一陽(yang)(yang)指(zhi)」除了可以完全(quan)對付(fu)歐(ou)陽(yang)(yang)鋒(feng)(feng)外,也可以祛百病、調虛實(shi),治療沉重內傷。
在(zai)不同小(xiao)說描述(shu)里有不同作(zuo)用,上(shang)(shang)(shang)官鼎小(xiao)說《沉沙谷》描述(shu):「全真(zhen)(zhen)(zhen)(zhen)教(jiao)」和(he)「少(shao)林(lin)派(pai)」是(shi)最敝帚自珍(zhen),天(tian)下(xia)所矚目的(de)(de)就是(shi)「先天(tian)罡氣(qi)」。全真(zhen)(zhen)(zhen)(zhen)與少(shao)林(lin)雖然(ran)在(zai)取勁(jing)上(shang)(shang)(shang)有柔剛之(zhi)別,但天(tian)下(xia)的(de)(de)武(wu)(wu)學(xue)是(shi)萬(wan)變不離(li)其(qi)宗,而(er)以(yi)「人」為原則的(de)(de)。況且(qie),兩(liang)派(pai)的(de)(de)「先天(tian)氣(qi)功(gong)(gong)」又是(shi)同屬一(yi)個范圍的(de)(de)事物。許多「全真(zhen)(zhen)(zhen)(zhen)派(pai)」的(de)(de)功(gong)(gong)訣上(shang)(shang)(shang)不夠份量(liang)的(de)(de)地方(fang)(fang),拿「少(shao)林(lin)心(xin)(xin)(xin)法」一(yi)加對照,便瞭(liao)然(ran)於胸(xiong)了(le),而(er)相反(fan)的(de)(de),「少(shao)林(lin)心(xin)(xin)(xin)法」的(de)(de)缺點(dian)也(ye)可以(yi)用全真(zhen)(zhen)(zhen)(zhen)之(zhi)長(chang)來(lai)(lai)補救。少(shao)林(lin)和(he)全真(zhen)(zhen)(zhen)(zhen)佛道兩(liang)門至高武(wu)(wu)學(xue)水乳(ru)交融,少(shao)林(lin)和(he)全真(zhen)(zhen)(zhen)(zhen)的(de)(de)心(xin)(xin)(xin)法一(yi)旦合并,舉世(shi)無敵!使用者:陸(lu)介《長(chang)干行》描述(shu):流(liu)落(luo)(luo)於關外(wai)「天(tian)池派(pai)」。當年「全真(zhen)(zhen)(zhen)(zhen)教(jiao)」仗(zhang)以(yi)威攝武(wu)(wu)林(lin),幾達(da)百馀年之(zhi)久,後來(lai)(lai)全真(zhen)(zhen)(zhen)(zhen)沒落(luo)(luo),這種武(wu)(wu)功(gong)(gong)失(shi)傳(chuan),方(fang)(fang)有少(shao)林(lin)武(wu)(wu)當等派(pai)興起(qi),算起(qi)來(lai)(lai),這「先天(tian)功(gong)(gong)」正(zheng)(zheng)是(shi)武(wu)(wu)學(xue)之(zhi)源。當掌力達(da)於極限時,能相觸無聲(sheng),卻最易傷(shang)人內腑(fu),這種功(gong)(gong)夫,有個名(ming)稱叫做「否(fou)極泰來(lai)(lai)」,正(zheng)(zheng)是(shi)物極必反(fan)的(de)(de)道理,掌力能不聞一(yi)些聲(sheng)響(xiang),空中暗勁(jing)橫流(liu),風力激蕩(dang)。使用者:「定天(tian)一(yi)戟」高戰(zhan)。