One man walking to a certain and unknown location is as less prone to deep thoughts as it is one man caught in a vivid and demonstrative conversation.
Such conversation is a simile of the walking because the speaker also wants to go somewhere, even if this location is in fact of an immaterial nature. Nonetheless, an unknown destination of a travel is still immaterial before it will be reached.
Who can distract its attention to the road followed by dedicating himself to long duration thoughts, even if he knows that those thoughts would help him to arrive at the intended location?
A deep thought is a waste of time in this case, and so it is in a conversation.
Therefore, whenever is used a conversational language, it appears the tendency to ignore deep thoughts. It is a common situation in philosophy, since it was borne in conversational context and often takes the form of convincing demonstrations.
Because of its duration, a deep thought moves so slowly, that becomes imperceptible its target. Its motion seems not to be a linear one, as the steps of demonstration are developed. Rather, it shows a movement of continuous retreat, which can be characterized as a circular movement around itself. But doing so, mind succeeds in imposing its proper movement. It ceases to borrow the way we behave in common travels to certain locations.
For this reason, conversational language is weak as regards the power of resisting to the surrounding contexts. It is closer to other elements of human behavior than to the way we think.
Moreover, the philosophers provided themselves with substitutive means of demonstration, ones that imitate the movement proper to deep thoughts. For instance, we have the definitions that tie the defined realities to propositional statements. They restrain our freedom of thinking beyond the limits of a certain interpretation of things, commanding us a continuous and seemingly circular reference to the definitions.
But the brevity and the limitation of definitions is just a hasty solution for introducing deep thoughts in our philosophical discourses. On the contrary, a deep thought should be able to a continuous redefinition of things discussed, as long it is needed to describe their thoroughly interconnection which is responsible for the circular motion of deep thoughts.