Ego autem puto difficillimum esse verbum novum sine mendo describere, cum manus et mens satis quietae non sunt.

Latin often leaves pronouns out, because the verb ending already shows the person. So puto by itself can mean I think.

When ego is added, it gives emphasis or contrast. Here, with autem also present, the sense is something like I, however, think... or but I think....

Autem usually means however, but, or on the other hand.

It is a postpositive word, which means it normally comes after the first word of its clause, not at the very beginning. So ego autem is the normal Latin order, even though English would usually say however, I... or but I....

Some adjectives ending in -ilis form their superlative with -limus rather than -issimus. Difficilis is one of them.

So:

• difficilis = difficult
• difficillimus = most difficult, very difficult

Here difficillimum is the neuter singular form required by the construction.

Yes. After verbs of thinking, saying, knowing, and similar ideas, Latin often uses an infinitive construction instead of a clause with that.

So puto ... esse means I think ... to be or more naturally I think that ... is.

In this sentence, the whole idea being thought is:

verbum novum sine mendo describere difficillimum esse

= to copy/write out a new word without error is very difficult

Because it goes with the infinitive phrase verbum novum sine mendo describere.

In Latin, an infinitive used like a noun is treated as neuter singular. So if to write a new word without error is the subject of esse, then the predicate adjective is also neuter singular:

• describere ... esse difficillimum
• to write/copy ... is very difficult

So difficillimum is not describing verbum by itself; it describes the whole action.

It is accusative singular.

That is because it is the direct object of describere. The verb describere means to write out, copy, describe, or set down, depending on context, and here it takes verbum novum as the thing being written or copied.

So:

• describere verbum novum = to write out/copy a new word

Not necessarily. This is a very common point of confusion.

Latin describere can mean to describe, but it can also mean to copy out, write down, transcribe, or set down in words. In this sentence, because of verbum novum and sine mendo, the sense is more like to copy/write out a new word correctly, not to describe a new word.

Sine mendo means without error, without a mistake, or without a fault.

The preposition sine takes the ablative case, so mendum becomes mendo in the ablative singular.

So:

• mendum = mistake, error
• sine mendo = without error

Here cum means when.

This is a straightforward temporal use, so the indicative is normal: cum ... non sunt = when ... are not.

Latin also has uses of cum with the subjunctive, especially for circumstantial or causal background, but that is not what is happening here. This sentence simply states the time or situation in which the action is difficult.

Because two singular nouns joined by et make a plural subject.

So:

• manus = hand
• mens = mind
• manus et mens = hand and mind

Since both nouns are feminine, the adjective is feminine plural: quietae. And the verb is plural as well: non sunt.

Here manus is singular: the hand. The sentence means hand and mind, not hands and minds.

The form manus can be nominative singular or nominative plural, so you have to tell from context. Here the pairing with singular mens strongly suggests singular manus.

Also, manus is a fourth-declension noun and is usually feminine, even though it ends in -us. Since both manus and mens are feminine, quietae is feminine plural.

Satis is an adverb meaning enough, sufficiently, or quite.

So satis quietae non sunt means are not sufficiently calm/steady. The idea is that the hand and mind are not calm enough for accurate writing.

In context, quietae can suggest not only calm but also steady or settled, which fits the idea of making mistakes while writing.