The Buddha's invitation to us is "to come and see" for ourselves what is true. Investigation is the "activity" of mindfulness. It's the activity of discernment. It illuminates the object. When things are brightly lit, what is already present is then clearly seen and known, and confusion is dissipated.
"EHI PASSIKA" "Some and See" investigation is the active aspect of mindfulness. It brings a clear discernment of our body-mind experience. Investigation is what lights up the truth for us.
Mindfulness is needed in all instances. It has the capacity to connect with and accept whatever phenomenon is presenting itself at any of the six sense doors without judgement, evaluation or the attachment of self-identification. Mindfulness is the "mother" of all the factors of enlightenment. It offers the great intimacy with experience that is needed for the door of truth to open.
The source of our awakening is right inside us. As we learn to listen deeply to the wisdom and purity of heart that is connected to the truth we are following the Buddha's instructions to be "be a lamp unto yourself."