There are many structural correlations in our experience. Not all of them motivate metaphors, but many do. When there is such a motivation, the metaphor seems natural. The reason it seems natural is that the pairing of the source and target domains is motivated by experience, as are the details of the mapping.
- Lakoff (1987), a pag.278

There are two ways in which a conceptual metaphor can be productive. The first is lexical. The words and fixed expressions of a language can code, that is, to be used to express aspects of a given conceptual metaphor to a greater or lesser extent. The number of conventional linguistic expressions that code a given conceptual metaphor is one measure of the productivity of the metaphor. In addition, the words and fixed expressions of a language can elaborate the conceptual metaphor. [...] We usually have extensive knowledge about source domain. [...] A second way in which a conceptual metaphor can be productive is that it can carry over details of that knowledge from the source domain to the target domain. We will refer to such carryovers as metaphorical entailments. Such entailments are part of our conceptual system. The constitute elaborations of conceptual metaphors. The central metaphor has a rich system of metaphorical entailments.
- Lakoff (1987), a pag.384

The structural aspect of a conceptual metaphor consists of a set of correspondences between a source domain and a target domain. These correspondences can be factored into two types: ontological and epistemic. Ontological correspondences are correspondences between the entities in the source domain and the corresponding entities in the target domain. [...] Epistemic correspondences are correspondences between knowledge about the source domain and knowledge about the target domain.
- Lakoff (1987), a pag.386-387

Conceptual metaphors are not mere flights of fancy, but can even have a basis in bodily experience.
- Lakoff (1987), a pag.409

A metaphor can be viewed as an experientially based mapping from an ICM in one domain to an ICM in another domain. This mapping defines a relationship between the idealized cognitive models of the two domains. It is very common for a word that designates an element of the source domain’s ICM to designate the corresponding element in the ICM of the target domain. The metaphorical mapping that relates the ICMs defines the relationship between the senses of the word. It is most common for the sense of the word in the source domain to be viewed as more basic.
- Lakoff (1987), a pag.417