src/Core/Configure.php
public static function load($key, $config = 'default', $merge = true)
    {
        $engine = static::getEngine($config);
        if (!$engine) {
            return false;
        }
        $values = $engine->read($key);

        if ($merge) {
            $values = Hash::merge(static::$values, $values);
        }

        return static::write($values);
    }
public static function load($key, $config = 'default', $merge = true)
    {
        $engine = static::getEngine($config);
        if (!$engine) {
            return false;
        }
        $values = $engine->read($key);

        if ($merge) {
            $values = Hash::merge(static::$values, $values);
        }

        return static::write($values);
    }
Loads stored configuration information from a resource. You can add
config file resource engines with `Configure::config()`.

Loaded configuration information will be merged with the current
runtime configuration. You can load configuration files from plugins
by preceding the filename with the plugin name.

`Configure::load('Users.user', 'default')`

Would load the 'user' config file using the default config engine. You can load
app config files by giving the name of the resource you want loaded.

```
Configure::load('setup', 'default');
```

If using `default` config and no engine has been configured for it yet,
one will be automatically created using PhpConfig.

@param string $key Name of configuration resource to load.
@param string $config Name of the configured engine to use to read the resource identified by $key.
@param bool $merge If config files should be merged instead of simply overridden.

@return bool False if file not found, true if load successful.