Boid.prototype.move = function() {
          // Rapha«l JS doesn't provide any way to GET the position once 
          // we've moved it so we'll need to manually track the position
          this.x += this.xVelocity;
          this.y += this.yVelocity;
          var border = 5;
          if(this.x <= border || this.x >= width - border) {
                  this.x -= this.xVelocity;                                        
                  this.x = Math.max(this.x, border);
                  this.x = Math.min(this.x, width - border);
                  this.xVelocity = -this.xVelocity;
                  this.x += this.xVelocity;
          }
          if(this.y <= border || this.y >= height - border) {
                  this.y -= this.yVelocity;
                  this.y = Math.max(this.y, border);
                  this.y = Math.min(this.y, height - border);
                  this.yVelocity = -this.yVelocity;
                  this.y += this.yVelocity;
          }
          this.circle.translate(this.xVelocity, this.yVelocity);
  }