4221. How from habit or practice such a nature is induced is clear from many considerations. It becomes such that one is not aware of having acquired the habit, such as that of speaking, of eating, of walking, all of which one learns, and without learning, could not possibly perform - likewise to look out for objects encountered while walking, to discern the character of others from their speech and facial expression, and to move one's arms. In regard to all the senses, such abilities are acquired by habit, which just shows that what is acquired by habit becomes so familiar that one is not conscious of having them. 1749, 15 April.
4221. How it is that from habit or actuality such a result is produced appears from a variety of similar things in regard to which a man is not aware that they are contracted by habit, as for instance his speaking, his eating or chewing, his walking, all which a man learns, and without learning could not do them. So it is also in respect to the avoidance of objects in one's way, the perception of the quality of others from their speech and face, and the motion of the arms; in fact, the case is the same in relation to all the senses, that certain results are contracted by habit which, from their being so familiar, one is not aware that they pertain to him. - 1749, April 15.
4221. Quomodo ex habitu seu actuali inducitur tale constat a permultis, fit tale ut homo nesciat quod traxerit habitu, ut loquela ejus, manducatio ejus, gressus ejus, quae omnia homo discit, si non disceret, non posset; similiter sibi cavere ab occursu dum ambulat; perspicere ex aliorum loquela et facie, quales: movere brachia, circa omnes sensus talia habitu trahuntur, inde constat solum, [id] quod ex habitu trahit, quod familiare fiat, ut nesciat quod habeat. 1749, 15 April.