本文主要是就所謂「天臺三大部」的《法華玄義》、《法華文句》與《摩訶止觀》以探討天臺大師智顗的心靈哲學。按智顗先就「無明一念心」一概念以說心的幻妄性，以交代生死流轉世界的生成。這是心的負面作用。心也有正面的作用，這便是認識事物，以至契會真理，故心是覺悟、成道、得解脫的根本。故心具有無明與法性兩個面相，這兩個面相都源自同一的心體。在與諸法的關係方面，智顗的說法是心具諸法，妄心固然具足諸法，淨心亦具足諸法。在這點上，智顗較著重前者，有所謂「一念三千」的說法。其意是，一念心總與多種境地的其中一種同時生起，也同時沈降。故一念心與三千種境界同起同寂。起是作用，寂是不作用。這作用是就心說的：在作用中，心與諸法同時生起；在不作用中，心與諸法同時寂滅。關於這點，智顗稱為「不可思議境」。這種說法，使心能保住諸法或存在，對存在有正面的肯定，不會走虛無主義的路線，使存在下墜以至泯滅。在實踐方面，智顗則提出一心三觀的觀法。這包括以心為被觀與以心來觀法兩種。前一種是就空、假、中三面來觀取一念妄心；後一種則以淨心為能觀，觀照對象的空、假、中三方面的面相。若觀法有次第，即先觀空，再觀假，最後觀中的，是次第觀，此是別教的觀法。若同時觀取空、假、中三相，「即空即假即中」地觀，則是圓頓的觀法，這是圓教的觀法。智顗自己所提倡的觀法，是圓教的觀法。

　　　　　This paper examines the so-called three main treatises of the T'ien-t'ai Sect, i.e. Fa Hua Hsuen Yi, Fa Hua Wen Chu, and Mou Ho Chih Kuan, to investigate Master Chih-i's mind philosophy. Master Chih-i first proposed the concept of "mind of one thought of ignorance" to explain the illusory nature of mind as the root of the birth of samsaric and changing world. This is the negative function of mind. Yet, mind has also a positive function, i.e. to recognize things and even to realize truth. Therefore, mind is also the root of enlightement, realizing Buddhahood, and obtaining liberation. In this context, mind has two dimensions of ignorance and dharmata which originate in the same mind. In regard to the relationship between mind and all things, Chih-i held that mind possesses all things. Although the ignorant mind possesses all things, the pure mind also possesses all things. In this point, Chih-i stressed more on the former. He proposed the concept of "three thousand worlds in one thought" which means that the mind of one thought always arises and disappears together with one of the multiple states. So, the mind of one thought arises and calms down with all things simultaneously. arising is function and calming down is no-function. In function, the mind and all things arises simultaneously: in no-function, the mind and all things calms down simultaneously. Chih-i called it "the inconceivable state". This argument shows that the mind can maintain all things and thus prevent then from totally negated. In the field of practice, Chih-i proposed the technique of "triple contemplation in one mind". It consists of two sides: the mind to be contemplated and the mind to contemplate. The former is to contemplate the ignorant mind of one thought by means of the triple contemplation: emptiness, provisionality and the middle. The latter is to use the pure mind as the mind to contemplate, i.e. to contemplate the three dimensions of emptiness, provisionality and the middle of the object. In the former contemplation, the practitioner has to contemplate emptiness first, provisionality next, and the middle last. This is the contemplation method of "pieh chiao". If one contemplates the three dimensions of emptiness, provisionality and the middle simultaneously, one has to contemplate the interpenetration and correlation of emptiness, provisionality and the middle. This is the contemplation method of sudden spontaneity. This is also the contemplation method of "yuan chiao". Chihi promoted the latter one.