Ernesto Grassi, a great humanist Italian philosopher, once said: "philosophy was a type of self knowledge." It is also regarded as a fulfillment of the inscription of the Apollo Temple at Delphi: Know Thyself.

According to Grassi, language is divided into two different forms of expression:

1) Rational: the measure of science whose final consequence is the demand for a mathematical symbolic language. Rational speech cannot be bound to times, places and personalities.

2) Rhetorical language which determines the premises themselves: the dominant assumptions, first assertions, hypotheses of formal discursive systems. Working with images of metaphores, rhetoric makes manifests.

Grassi reveals the philosophical importance of the Latin-Humanist tradition. It was Cicero who understood rhetoric as ingenium, as the language-based human capacity to "surpass what lies before us in our sensory awareness" by catching sights of relationships, of similitudiness among things.

Rhetoric is ingenious activity itself, whose essential characteristic is celeritas, manifested in discerning speech. The root of this discerning speech is metaphor (metapherein: transfer, carry accross). An empirical observation takes place through the reduction of sensory phenomenon to types of meanings existing in the living being; this reduction consists in the 'transferring' of a meaning to sensory phenomena.

Giambattista Vico takes the object of philosophy to be speculation about history and not nature, because man makes history himself but does not make nature. The world of civil society has been made by men, its principles are therefore to be found within the modifications of our own human mind.

Nature appears to us only in its meaning with reference to satisfying our existential needs. A relationship, similitudo, between what the senses reveal to us and our needs.

In classical Greek thought, Phytagoras set forth the proposition that the similar can be grasped only through something similar (similia similibus comprehendere).

Insight into "common" or shared characteristics makes possible the lending of meanings that allow things to appear in a way that i shuman. Such capacity is characteristic of fantasy which lets the human world appear. For this reason it is expressed originally in metaphors, i.e. in the figurative lending of meanings.

Fantasy collects from the senses and connects and enlarges to exaggeration the sensory of effects of natural appearances and makes luminous images from them, in order to suddenly blind the mind with lightning bolts and thereby to conjure up human passions in the ringing and thunder of this astonishment. The metaphor is the original form of the interpretative act itself, which raises from the particular to the general through representation in an image.

An attempt to find an answer to the question how the human mind can attain the fundamental union of res and verba (content and form), with the role of image, of the mental "appearance", designated with the concepts "fantasy and imagination".

Fantasy, as the gift of imagination, is first brought into connection with a "condition of light". Further, fantasy appears as the soul's power to create images, fantasy itself is fed with the images provided by the senses. Fantasy, or imagination, assumes an important function. First, it realizes itself in the sphere of the manifold sensory shapes by making a selection of them. The power of imagination reaches the higher spheres of the mind insofar as it can put at the disposal of the ratio and the intellect the images it has acquired through the senses.

Animals derive their behaviour directly from memory and fantasy because they command no higher faculties. Meanwhile, men subjects the images of fantasy to his "mind", so that the sensory images are interpreted in a human manner, and accordingly the passions also are interpreted in a human manner. Fantasy thereby designs the "potential" meanings of the images, which are then illuminated and defined by the light of intellect, to be preserved in the mental sphere of man. According to Gianfrancesco Pico, fantasy must be put under the domain of mental light. That light appears as a divine gift; its function is to reveal the human world.

Aristotle defines knowdlege and conviction as follows: the rational belilef [pistis] arising from demonstration: One believes and knows something when a deduction is carried out, which becomes proof. Proof is emphasized by giving the reason. The reason becomes evident in connection with the deduction, which starts from premises and depends on their validity.

To prove is to show something to be something, on the basis of something. Vico claims the aim of philosphy is the problem of "finding", he identifies the theory of "finding" with "topical philosophy".