This is a classic lateral thinking puzzle that requires us to reconsider the common definitions of the words "container" and "vanished." Here is a step-by-step logical breakdown to arrive at the solution.

The puzzle presents two key concepts that must be satisfied by a single answer:

1. It must be a "Container." A container is typically defined as an object that holds or encloses something. However, for a riddle, we must think more broadly. A container can be anything that defines a space or holds a concept, not just a physical box with walls.
2. It must have "Vanished." This implies that the container, in its entirety, ceases to exist or is no longer perceivable. It disappears completely.

Step 2: Analyze the Word "Container" Beyond the Literal

Let's expand our definition of a container:

• Physical Containers: A box, a bottle, a bag, a room, a swimming pool.
• Abstract/Conceptual Containers: A word (contains letters/sound), a memory (contains thoughts), a hole (contains emptiness/earth), a shadow (contains the absence of light).

Step 3: Analyze the Word "Vanished" in Context

"Vanished" means to disappear suddenly and completely. Let's consider how different containers might vanish:

• A physical bottle can be emptied, but it doesn't vanish; it just becomes an empty bottle.
• A room can be demolished, but the act of vanishing is destructive, not inherent to its nature.
• A memory can be forgotten, but this is a slow fade, not a sudden vanishing.

Step 4: Synthesize the Concepts and Identify the Solution

We are looking for something that is fundamentally a container and is also defined by its ability to vanish. Let's evaluate the conceptual containers from Step 2 against the "vanished" criterion.

• A Hole: A hole is a container of emptiness. It can vanish if you fill it in. This is a good candidate, but the act of vanishing requires an external action (filling it).
• A Memory: A memory is a container of past events. It can vanish through forgetting. However, this process is gradual and not guaranteed to be complete.

Now, let's consider the strongest candidate:

• A Shadow:
  • Is it a container? Yes. A shadow is a defined area or shape that "contains" or is defined by the absence of light. It is a boundary within which light cannot pass. It holds the concept of darkness.
  • Does it vanish? Yes, absolutely. A shadow has no physical substance of its own. It is entirely dependent on three things: a light source, an object to block the light, and a surface to receive the shadow. If you remove any one of these elements, the shadow vanishes instantly and completely, leaving no trace. It literally disappears into nothingness.

Conclusion

The object that is both a container and can vanish is a shadow. It is a perfect container for the absence of light, and its existence is so ephemeral that it vanishes the moment the conditions that create it are no longer met. This solution cleverly satisfies both conditions of the riddle by reinterpreting the words in a non-literal way.