Johan Amos Comenius, (1592-1671): "Let nothing be prescribed as a memory-task that has not previously been impressed by means of the ear, the eye, the tongue, the hand. Let nothing be learned by authority, but by demonstration, sensible and rational. Above all, never teach words without things, even in the vernacular; and whatever the pupils see, hear, taste, or touch, let them name. The tongue and the intelligence should advance on parallel lines. For the beginning of knowledge is from pure sense, not from words; and truth and certitude are testified to by the evidence of the senses. The senses are the most faithful stewards of the memory. The study of language should run parallel with the study of things, especially in youth, for we desire to form men, not parrots."

Friedrich Froebel, (1782-1852): "Man only understands thoroughly that which he is able to produce."

Sir James Chrichton Browne (1840-1938): "It is plain that the highest functional activity of these motor centres is a thing to be aimed at with a view to general mental power as well as with a view to muscular expertness; and as the hand centres hold a prominent place among the motor centres, and are in relation with an organ in which prehension, in touch and in a thousand different combinations of movement, adds enormously to our intellectual resources, thought,and sentiments, it is plain that the highest possible functional activity of these hand centres is of paramount importance not less to mental grasp than to industrial success." "Depend upon it that much of the confusion of thought... in highly educated men and women is dependent on defective or misdirected muscular training, and that the thoughtful and diligent cultivation of (the hand) is conducive to breadth of mind as well as to breadth of shoulders."

I couldn't have said it better myself.

One more from Gustaf Larsson: "Tools are instruments by which the hands give expression to thought."