"Every tool is a weapon if you hold it right." Ani DiFranco
"Put away your tool." (Shakespeare) 

"A tool is always intrinsically simple, however elaborate its mechanism may be, but a work of art, which is a complex of many stages and levels of criss-crossed intentions, is always intrinsically complicated, however simple its effect may seem." George Kubler, The Shape of Time, p. 11. 

insert scan of hammer
Tool and organ:

Leroi-Gourhan in Gesture and Speech describes the tool as process of exteriorization of the body. Erect posture leads to new relation between face / hand / tool . 

(see prosthesis

Henri Focillon describes the relationship between the hand and the tool as a human familiarity, whose harmony is composed of the subtlest give-and-take, not just a matter of habit. (The Life of Forms in Art, p109.) "Once the hand has need of this self-extension in matter, the tool itself becomes what the hand makes it. The tool is more than a machine. " The "exact meeting place" of form, matter, tool, and hand is the touch. 

Heidegger discusses tools in Being and Time, claiming that there is no such thing as "a" technology or tool apart from its context of involvements and referentialities. For phenomenological analysis, the human-technology relation in the tool is an embodiment relation, as opposed to a hermeneutic or alterity relation. (?) "Equipment is essentially 'something in order to'." (p.97) Heidegger finds an embodied model for understanding the generation of knowledge in the praxis of tool use. He describes the everyday pragmatic relation of equipment or tools as ready-to-hand . (a condition similar to Levi-Strauss's description of bricolage ? see myth.) Heidegger calls the more disengaged, knowledge relation the present-at-hand . While philosophy might generally privilege the latter, epistemological object, Heidegger explores the ready-to-hand as part of a totality of involvements in which lurks an ontological relationship to the world. (This is the basis of his inversion of the science/ technology relation.)

Heidegger's often analyzed example is the hammer. Before being an epistemological object, its being-a-hammer is primarily in relation to work. The hammer in use achieves what Don Ihde calls " instrumental transparency." It "withdraws" when in use, but becomes conspicuous again when broken or missing. (see forgetting) Its dynamic being is contextual. It belongs to a tool-context that includes the nails, the shingles, the carpentry project, etc., which contains, at least implicitly, a way of relating to an entire environment and with it to an implicit "world." In the words of Abraham Maslow, "If the only tool you have is a hammer, you tend to treat everything as if it were a nail." 

Ihde qualifies his notion of "instrumental transparency" with the observation that this transparency is never total, that "technology always carries with it a partial or quasi-transparency, which is the price of the extension of magnification that technologies give." (Technology and Lifeworld, p.75) The romanticizing of technology (whether utopian or dystopian) hinges on this desire for total transparency.

Is the difference between the tool and the machine as simple as its source of power: muscular (human or animal) in the former case, and non-organic in the latter ? 

For Marx, the tool is the instrument of labor "which seizes upon the object of labor and modifies it as desired." (Capital, p494) and the machine is a mechanism that, after being set in motion, performs with its tools the same operation as the worker formerly did with similar tools." (p.495) The machine replaces the worker, not the tool. "it is not what is made but how, and by what instruments of labor, that distinguishes different economic epochs. Instruments of labor...also indicate the social relations within which men work." (p286) The manufacturing period (which is prior to large-scale mechanical manufacture) " simplifies, improves and multiplies the instruments of labor by adapting them to the exclusive and special functions of each kind of worker. It thus creates at the same time the material conditions for the existence of machinery, which consists of a combination of simple instruments." (p.461) 

Is the combination of the human and the tool a machine?