It would appear that Lucilius wants a wider variety of books to read and that the supply is "scant" where he is located. He then seems to suggest to Seneca that he write more to send to him. Seneca cautiously advises Lucilius to remember that he too (Seneca) is still learning.
whatever the quality of my works may be, read them as if I were still seeking, and were not aware of, the truth, and were seeking it obstinately, too.
Seneca notes that much of his knowledge is attributed to "great men," but he also notes that these "great men" have also left "problems whose solution is still to be sought." He continues,
They lost much time in quibbling about words and in sophistical argumentation; all that sort of thing exercises the wit to no purpose. We tie knots and bind up words in double meanings, and then try to untie them.
We don't have time to stew. Our time should be kept focused on matters at hand; on duty.
We should rather proceed with our whole souls towards the point where it is our duty to take heed lest things, as well as words, deceive us.
The point is that we should get to the heart of the matter - understanding what is good and evil; ensuring that we are following the path to virtue and not to vice and ensuring that we do not fool ourselves into thinking we are virtuous when in fact we are full of vice.
Why, pray, do you discriminate between similar words, when nobody is ever deceived by them except during the discussion? It is things that lead us astray: it is between things that you must discriminate. We embrace evil instead of good; we pray for something opposite to that which we have prayed for in the past. Our prayers clash with our prayers, our plans with our plans ... Vices creep into our hearts under the name of virtues, rashness lurks beneath the appellation of bravery, moderation is called sluggishness, and the coward is regarded as prudent; there is great danger if we go astray in these matters. So stamp them with special labels.
Virtue - excellence of soul - arete leads to eudaimonia - a good spirit. Here is wisdom if you can teach and learn what a happy man is.
he whose possessions are all in his soul, who is upright and exalted, who spurns inconstancy, who sees no man with whom he wishes to change places, who rates men only at their value as men, who takes Nature for his teacher, conforming to her laws and living as she commands, whom no violence can deprive of his possessions, who turns evil into good, is unerring in judgment, unshaken, unafraid, who may be moved by force but never moved to distraction, whom Fortune when she hurls at him with all her might the deadliest missile in her armoury, may graze, though rarely, but never wound. For Fortune's other missiles, with which she vanquishes mankind in general, rebound from such a one, like hail which rattles on the roof with no harm to the dweller therein, and then melts away.
On this aim should the Stoic place his gaze. And it requires constant attention and focus. Therefore, the Stoic does not have time for "the superfluous" - they must live now and stop "preparing to live."
transfer your efforts to making it clear to all men that the search for the superfluous means a great outlay of time, and that many have gone through life merely accumulating the instruments of life? Consider individuals, survey men in general; there is none whose life does not look forward to the morrow. "What harm is there in this," you ask? Infinite harm; for such persons do not live, but are preparing to live. They postpone everything.