SB 4.29.63

yathānumīyate cittam
 ubhayair indriyehitaiḥ
evaṁ prāg-dehajaṁ karma
 lakṣyate citta-vṛttibhiḥ
Synonyms: 
yathā — as; anumīyate — can be imagined; cittam — one’s consciousness or mental condition; ubhayaiḥ — both; indriya — of the senses; īhitaiḥ — by the activities; evam — similarly; prāk — previous; dehajam — performed by the body; karma — activities; lakṣyate — can be perceived; citta — of consciousness; vṛttibhiḥ — by the occupations.
Translation: 
One can understand the mental or conscious position of a living entity by the activities of two kinds of senses — the knowledge-acquiring senses and the executive senses. Similarly, by the mental condition or consciousness of a person, one can understand his position in the previous life.
Purport: 

There is an English proverb that says, “The face is the index of the mind.” If one is angry, his anger is immediately expressed in his face. Similarly, other mental states are reflected by the actions of the gross body. In other words, the activities of the gross body are reactions of the mental condition. The mind’s activities are thinking, feeling and willing. The willing portion of the mind is manifest by the activities of the body. The conclusion is that by the activities of the body and senses, we can understand the condition of the mind. The condition of the mind is affected by past activities in the past body. When the mind is joined with a particular sense, it immediately becomes manifest in a certain way. For instance, when there is anger in the mind, the tongue vibrates so many maledictions. Similarly, when the mind’s anger is expressed through the hand, there is fighting. When it is expressed through the leg, there is kicking. There are so many ways in which the subtle activities of the mind are expressed through the various senses. The mind of a person in Kṛṣṇa consciousness also acts in a similar way. The tongue chants Hare Kṛṣṇa, the mahā-mantra, the hands are raised in ecstasy, and the legs dance in Kṛṣṇa consciousness. These symptoms are technically called aṣṭa-sāttvika-vikāra. Sāttvika-vikāra is transformation of the mental condition in goodness or sometimes transcendental ecstasy.