# Every quantifier Learn how to check that all items in a collection satisfy a condition. This checks whether all elements in a collection satisfy a given condition. Note that this quantifier always returns true for empty collections. This is known in logic as [vacuous truth](https://en.wikipedia.org/wiki/Vacuous_truth), meaning that the quantifier is satisfied because there are no elements in the collection that do not satisfy the condition. > **Is every unicorn in the room shining?** > > This might sound funny, but since there are no unicorns in the room, there's no unicorn that isn't shining. So, technically, they all are! ## Syntax This quantifier has the following syntax: ```cql every /**/ in /**/ satisfies /**/ ``` Either *satisfy* or *satisfies* can be used interchangeably: ```cql every /**/ in /**/ satisfy /**/ ``` You can also specify a name to refer to the index of the element in the collection: ```cql every /**/ in /**/ indexed by /**/ satisfies /**/ ``` You must replace the `/**/` and `/**/` placeholders with a [valid identifier](/reference/cql/syntax#identifiers). These variables will refer to the element and its index in the collection, as exemplified in the following section. ## Examples Here is a basic example that checks if all numbers in a collection are even: ```cql every number in [2, 4, 6] satisfies number mod 2 is 0 // true ``` The following example shows how to use the index of the element in the condition: ```cql every item in cart indexed by index satisfies item's brand is "Apple" and index >= 1 ``` In the above example, it checks whether the user only added Apple products as the second or subsequent item in the cart.