A clutch of eggs

Today is all about da! Most often translated as "of", it has a very specific use all to itself. It mustn't be confused with de, which is another word often translated as "of". Strap in till the end to learn the true power of grasping the difference between the two.

Basically, "da" is used to relate some quantity to some type of thing. In a phrase:

x da y
x of y

x is some quantity and y is a type of thing. The above phrase shows that you have x amount of y. x must be a quantity and y must be an indefinite type.

So x is easy, it could be a bunch, a little, a dozen, a litre, a box, a lot, a flask, a fist-full, you get the idea!

What’s y though? What’s an indefinite type? The answer is: y must only be a type of thing, a concept of a thing, it can’t be a particular group of things. So in the title "a clutch of eggs", y is eggs. "Eggs" is indefinite. "Eggs" does not refer to any particular eggs at all. It’s just talking about the concept of eggs. Then with da we take some portion of this type of thing.

skatolo da ovoj 
a box of eggs

If we’re talking about certain eggs, and not just the general idea of eggs, for y, then da cannot be used:

mi ŝtelis skatolon el viaj ovoj
I stole a box of your eggs

Here y is "your eggs", those are particular eggs, not just the concept of eggs. Therefore, da cannot be used!

There are a few nitty gritty bits to think about. Numbers are quantities, but they are allowed to directly refer to nouns, so you don’t need a da:

mi havas du ovojn 
I have two eggs

The exception is when you’ve got a number that is in noun form (ending in “o”), then it acts like a grouping:

mi havas milionon da ovoj
I have a million (of)  eggs.

If x is an adjective (a-word), it is allowed to directly describe the noun y, so you do not use da:

mi havas multajn ovojn
I have a lot of eggs

versus:

mi havas multe/multon da ovoj
I have a lot of eggs

And now the most exciting bit. Both the phrases glaso da vino and glaso de vino are possible! Why?

Because they mean different things! According to the trusty PMEG:

Glaso de vino is more like "wine glass", a glass in which wine was present, or is usually present. But glaso da vino uses glaso as a quantity; it’s a glass-sized amount of wine, or a glass full of wine.

In such cases, da and de answer different questions:

how many soldiers are there?
grupo da soldatoj 

what kind of group is that?
grupo de soldatoj 

All hanging on the difference in a single vowel. What power!