As You Like It
Act 2 scene 7
Jaques is revealing an off-stage event, thus we should be aware that we are getting this information through Jaques' point of view, telling us something about Jaques as a character.
As with any fool, Touchstone can figure out what his audience wants and give it to him. Touchstone is probably putting Jaques on, but Jaques is taking him seriously. Jaques wants the role of a fool, the ability to speak truth. yet he does not understand the world completely because he sees it through the filter of his melancholy; he wants to "cleanse the foul body of th' infected world, If they will patiently receive my medicine." This speech connects him to Rosalind who will cure Orlando of his love-sickness if he will only go along with her medication.
[This is the answer to the question.]
Orlando needed to learn gentility, civility, and here Duke Senior gives him his first lesson in the forest. Later Rosalind will complete his education.
Jaques is regurgitating Duke Senior's speech just a few lines before. Jaques' version is very cynical, not sentimental at all about the infant or the schoolboy, etc. His last line, "sans teeth, sans eyes, sans taste, sans everything" is the most bleak view of all. Yet when the speech is over, Shakespeare immediately has Orlando enter with Old Adam, who contradict this satiric view of old age.