Final answer:
"Lennox and the lord are thinking similarly about recent events." Lennox is indicating that his previous comments have reached the lord's thoughts, suggesting they both share suspicions about the recent tragedies and the rise of Macbeth's power.
Step-by-step explanation:
When Lennox says, "My former speeches have but hit your thoughts," he is suggesting that the ideas and suspicions he has previously articulated are in alignment with what the lord is already thinking. Lennox indicates that his remarks resonate with the lord's perceptions and interpretations of the recent tragic events surrounding the characters in Macbeth. This connection implies that both are questioning the legitimacy and morality of Macbeth's actions and the convenient timing of the deaths of those who could threaten his power.
Here, Lennox is subtly criticizing the circumstance under which King Duncan was murdered ('The gracious Duncan/ Was pitied of Macbeth: marry, he was dead'), and the suspicious death of the 'right-valiant Banquo' to hint at Macbeth's deceit and the unnatural series of events that have led to him becoming king.