Final answer:
The phrase 'free to contemplate and aspire to the knowledge of the unknown' supports Plato's argument that truth is attained through the unfettered use of reason, in a state detached from bodily distractions. This ideal state enables the pursuit of pure knowledge in the abstract realm of the Forms, aligning with Plato's view of philosophy as a rigorous, abstract quest for truth.
Step-by-step explanation:
The phrase "free to contemplate and aspire to the knowledge of the unknown" supports the speaker's claim in Plato's The Republic by suggesting that a person can attain truth when the rational part of the soul is unencumbered by the distractions of bodily desires and emotions. According to Plato, accessing truth requires abstract thinking and reasoning, a process which he sees as akin to the soul separating from the body. Therefore, this phrase supports the notion that in a state of pure contemplation and aspiration towards the unknown, free from the influence of the bodily senses and irrational desires, the soul is most likely to achieve understanding of the Forms and the true nature of reality.
In the context of the excerpt from The Republic, when Plato discusses laying the appetites to sleep and pacifying the passionate element, what he's emphasizing is the idea that reason must be the guiding force, leading one to philosophical reflection and ultimately to truth. In doing so, Plato aligns with the Platonic tradition that the material world is transient and imperfect, whereas the real knowledge that should be attained is abstract and invariant, such as mathematics and ethics, which exist in the realm of the Forms.